[PATCH 0/5] Expand selftest utils

[PATCH 0/5] Expand selftest utils

[Benjamin Gray]

Started this when writing tests for a feature I'm working on, needing a way to
read/write numbers to system files. After writing some utils to safely handle
file IO and parsing, I realised I'd made the ~6th file read/write implementation
and only(?) number parser that checks all the failure modes when expecting to
parse a single number from a file.

So these utils ended up becoming this series. I also modified some other test
utils I came across while doing so. My understanding is selftests are not expected
to be backported, so I wasn't concerned about only introducing new utils and leaving
the existing implementations be.

V3:	* Add reviewed-by from previous version
	* Fix write(2) call to include creation mode
V4:	* Drop patches merged in v3
	* Miscellaneous refactoring
	* Bigger changes mentioned on the relevant patch

Benjamin Gray (5):
  selftests/powerpc: Add generic read/write file util
  selftests/powerpc: Add read/write debugfs file, int
  selftests/powerpc: Parse long/unsigned long value safely
  selftests/powerpc: Add {read,write}_{long,ulong}
  selftests/powerpc: Add automatically allocating read_file

 tools/testing/selftests/powerpc/dscr/dscr.h   |  34 +-
 .../selftests/powerpc/dscr/dscr_sysfs_test.c  |  25 +-
 .../testing/selftests/powerpc/include/utils.h |  20 +-
 .../selftests/powerpc/nx-gzip/gzfht_test.c    |  52 +--
 tools/testing/selftests/powerpc/pmu/lib.c     |  34 +-
 .../selftests/powerpc/ptrace/core-pkey.c      |  28 +-
 .../selftests/powerpc/security/entry_flush.c  |  12 +-
 .../selftests/powerpc/security/rfi_flush.c    |  12 +-
 .../powerpc/security/uaccess_flush.c          |  18 +-
 .../selftests/powerpc/syscalls/Makefile       |   2 +-
 .../selftests/powerpc/syscalls/rtas_filter.c  |  81 +---
 tools/testing/selftests/powerpc/utils.c       | 412 +++++++++++++++---
 12 files changed, 431 insertions(+), 299 deletions(-)


base-commit: ca272751ba18ca8f137af631cbc9f3f987fab6e3
--
2.39.1

[PATCH 1/5] selftests/powerpc: Add generic read/write file util

[Benjamin Gray]

File read/write is reimplemented in about 5 different ways in the
various PowerPC selftests. This indicates it should be a common util.

Add a common read_file / write_file implementation and convert users
to it where (easily) possible.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>

---

v4:	* Set errno as expected by many users that call perror() if
	  it fails (e.g., read_debugfs_file users in powerpc/security)
---
 tools/testing/selftests/powerpc/dscr/dscr.h   |  33 ++---
 .../selftests/powerpc/dscr/dscr_sysfs_test.c  |  21 +--
 .../testing/selftests/powerpc/include/utils.h |   2 +
 .../selftests/powerpc/nx-gzip/gzfht_test.c    |  48 +++----
 tools/testing/selftests/powerpc/pmu/lib.c     |  31 ++--
 .../selftests/powerpc/ptrace/core-pkey.c      |  28 ++--
 tools/testing/selftests/powerpc/utils.c       | 133 +++++++++++-------
 7 files changed, 128 insertions(+), 168 deletions(-)

diff --git a/tools/testing/selftests/powerpc/dscr/dscr.h b/tools/testing/selftests/powerpc/dscr/dscr.h
index b703714e7d98..aaa2b0d89f7e 100644
--- a/tools/testing/selftests/powerpc/dscr/dscr.h
+++ b/tools/testing/selftests/powerpc/dscr/dscr.h
@@ -64,48 +64,31 @@ inline void set_dscr_usr(unsigned long val)
 /* Default DSCR access */
 unsigned long get_default_dscr(void)
 {
-	int fd = -1, ret;
-	char buf[16];
+	int err;
+	char buf[16] = {0};
 	unsigned long val;
 
-	if (fd == -1) {
-		fd = open(DSCR_DEFAULT, O_RDONLY);
-		if (fd == -1) {
-			perror("open() failed");
-			exit(1);
-		}
-	}
-	memset(buf, 0, sizeof(buf));
-	lseek(fd, 0, SEEK_SET);
-	ret = read(fd, buf, sizeof(buf));
-	if (ret == -1) {
+	err = read_file(DSCR_DEFAULT, buf, sizeof(buf) - 1, NULL);
+	if (err) {
 		perror("read() failed");
 		exit(1);
 	}
 	sscanf(buf, "%lx", &val);
-	close(fd);
 	return val;
 }
 
 void set_default_dscr(unsigned long val)
 {
-	int fd = -1, ret;
+	int err;
 	char buf[16];
 
-	if (fd == -1) {
-		fd = open(DSCR_DEFAULT, O_RDWR);
-		if (fd == -1) {
-			perror("open() failed");
-			exit(1);
-		}
-	}
 	sprintf(buf, "%lx\n", val);
-	ret = write(fd, buf, strlen(buf));
-	if (ret == -1) {
+
+	err = write_file(DSCR_DEFAULT, buf, strlen(buf));
+	if (err) {
 		perror("write() failed");
 		exit(1);
 	}
-	close(fd);
 }
 
 double uniform_deviate(int seed)
diff --git a/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c b/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
index f20d1c166d1e..c350f193830a 100644
--- a/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
+++ b/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
@@ -12,24 +12,13 @@
 
 static int check_cpu_dscr_default(char *file, unsigned long val)
 {
-	char buf[10];
-	int fd, rc;
+	char buf[10] = {0};
+	int rc;
 
-	fd = open(file, O_RDWR);
-	if (fd == -1) {
-		perror("open() failed");
-		return 1;
-	}
+	rc = read_file(file, buf, sizeof(buf) - 1, NULL);
+	if (rc)
+		return rc;
 
-	rc = read(fd, buf, sizeof(buf));
-	if (rc == -1) {
-		perror("read() failed");
-		close(fd);
-		return 1;
-	}
-	close(fd);
-
-	buf[rc] = '\0';
 	if (strtol(buf, NULL, 16) != val) {
 		printf("DSCR match failed: %ld (system) %ld (cpu)\n",
 					val, strtol(buf, NULL, 16));
diff --git a/tools/testing/selftests/powerpc/include/utils.h b/tools/testing/selftests/powerpc/include/utils.h
index e222a5858450..70885e5814a8 100644
--- a/tools/testing/selftests/powerpc/include/utils.h
+++ b/tools/testing/selftests/powerpc/include/utils.h
@@ -33,6 +33,8 @@ void *get_auxv_entry(int type);
 
 int pick_online_cpu(void);
 
+int read_file(const char *path, char *buf, size_t count, size_t *len);
+int write_file(const char *path, const char *buf, size_t count);
 int read_debugfs_file(char *debugfs_file, int *result);
 int write_debugfs_file(char *debugfs_file, int result);
 int read_sysfs_file(char *debugfs_file, char *result, size_t result_size);
diff --git a/tools/testing/selftests/powerpc/nx-gzip/gzfht_test.c b/tools/testing/selftests/powerpc/nx-gzip/gzfht_test.c
index 095195a25687..fbc3d265155b 100644
--- a/tools/testing/selftests/powerpc/nx-gzip/gzfht_test.c
+++ b/tools/testing/selftests/powerpc/nx-gzip/gzfht_test.c
@@ -146,49 +146,37 @@ int gzip_header_blank(char *buf)
 /* Caller must free the allocated buffer return nonzero on error. */
 int read_alloc_input_file(char *fname, char **buf, size_t *bufsize)
 {
+	int err;
 	struct stat statbuf;
-	FILE *fp;
 	char *p;
 	size_t num_bytes;
 
 	if (stat(fname, &statbuf)) {
 		perror(fname);
-		return(-1);
-	}
-	fp = fopen(fname, "r");
-	if (fp == NULL) {
-		perror(fname);
-		return(-1);
+		return -1;
 	}
+
 	assert(NULL != (p = (char *) malloc(statbuf.st_size)));
-	num_bytes = fread(p, 1, statbuf.st_size, fp);
-	if (ferror(fp) || (num_bytes != statbuf.st_size)) {
+
+	err = read_file(fname, p, statbuf.st_size, &num_bytes);
+	if (err) {
 		perror(fname);
-		return(-1);
+		goto fail;
 	}
+
+	if (num_bytes != statbuf.st_size) {
+		fprintf(stderr, "Actual bytes != expected bytes\n");
+		err = -1;
+		goto fail;
+	}
+
 	*buf = p;
 	*bufsize = num_bytes;
 	return 0;
-}
 
-/* Returns nonzero on error */
-int write_output_file(char *fname, char *buf, size_t bufsize)
-{
-	FILE *fp;
-	size_t num_bytes;
-
-	fp = fopen(fname, "w");
-	if (fp == NULL) {
-		perror(fname);
-		return(-1);
-	}
-	num_bytes = fwrite(buf, 1, bufsize, fp);
-	if (ferror(fp) || (num_bytes != bufsize)) {
-		perror(fname);
-		return(-1);
-	}
-	fclose(fp);
-	return 0;
+fail:
+	free(p);
+	return err;
 }
 
 /*
@@ -399,7 +387,7 @@ int compress_file(int argc, char **argv, void *handle)
 	assert(FNAME_MAX > (strlen(argv[1]) + strlen(FEXT)));
 	strcpy(outname, argv[1]);
 	strcat(outname, FEXT);
-	if (write_output_file(outname, outbuf, dsttotlen)) {
+	if (write_file(outname, outbuf, dsttotlen)) {
 		fprintf(stderr, "write error: %s\n", outname);
 		exit(-1);
 	}
diff --git a/tools/testing/selftests/powerpc/pmu/lib.c b/tools/testing/selftests/powerpc/pmu/lib.c
index 88690b97b7b9..960915304a65 100644
--- a/tools/testing/selftests/powerpc/pmu/lib.c
+++ b/tools/testing/selftests/powerpc/pmu/lib.c
@@ -190,38 +190,23 @@ int parse_proc_maps(void)
 
 bool require_paranoia_below(int level)
 {
+	int err;
 	long current;
-	char *end, buf[16];
-	FILE *f;
-	bool rc;
+	char *end;
+	char buf[16] = {0};
 
-	rc = false;
-
-	f = fopen(PARANOID_PATH, "r");
-	if (!f) {
-		perror("fopen");
-		goto out;
-	}
-
-	if (!fgets(buf, sizeof(buf), f)) {
+	err = read_file(PARANOID_PATH, buf, sizeof(buf) - 1, NULL);
+	if (err) {
 		printf("Couldn't read " PARANOID_PATH "?\n");
-		goto out_close;
+		return false;
 	}
 
 	current = strtol(buf, &end, 10);
 
 	if (end == buf) {
 		printf("Couldn't parse " PARANOID_PATH "?\n");
-		goto out_close;
+		return false;
 	}
 
-	if (current >= level)
-		goto out_close;
-
-	rc = true;
-out_close:
-	fclose(f);
-out:
-	return rc;
+	return current < level;
 }
-
diff --git a/tools/testing/selftests/powerpc/ptrace/core-pkey.c b/tools/testing/selftests/powerpc/ptrace/core-pkey.c
index 4e8d0ce1ff58..f6f8596ce8e1 100644
--- a/tools/testing/selftests/powerpc/ptrace/core-pkey.c
+++ b/tools/testing/selftests/powerpc/ptrace/core-pkey.c
@@ -348,15 +348,11 @@ static int parent(struct shared_info *info, pid_t pid)
 
 static int write_core_pattern(const char *core_pattern)
 {
-	size_t len = strlen(core_pattern), ret;
-	FILE *f;
+	int err;
 
-	f = fopen(core_pattern_file, "w");
-	SKIP_IF_MSG(!f, "Try with root privileges");
-
-	ret = fwrite(core_pattern, 1, len, f);
-	fclose(f);
-	if (ret != len) {
+	err = write_file(core_pattern_file, core_pattern, strlen(core_pattern));
+	if (err) {
+		SKIP_IF_MSG(err == -EPERM, "Try with root privileges");
 		perror("Error writing to core_pattern file");
 		return TEST_FAIL;
 	}
@@ -366,8 +362,8 @@ static int write_core_pattern(const char *core_pattern)
 
 static int setup_core_pattern(char **core_pattern_, bool *changed_)
 {
-	FILE *f;
 	char *core_pattern;
+	size_t len;
 	int ret;
 
 	core_pattern = malloc(PATH_MAX);
@@ -376,22 +372,14 @@ static int setup_core_pattern(char **core_pattern_, bool *changed_)
 		return TEST_FAIL;
 	}
 
-	f = fopen(core_pattern_file, "r");
-	if (!f) {
-		perror("Error opening core_pattern file");
-		ret = TEST_FAIL;
-		goto out;
-	}
-
-	ret = fread(core_pattern, 1, PATH_MAX - 1, f);
-	fclose(f);
-	if (!ret) {
+	ret = read_file(core_pattern_file, core_pattern, PATH_MAX - 1, &len);
+	if (ret) {
 		perror("Error reading core_pattern file");
 		ret = TEST_FAIL;
 		goto out;
 	}
 
-	core_pattern[ret] = '\0';
+	core_pattern[len] = '\0';
 
 	/* Check whether we can predict the name of the core file. */
 	if (!strcmp(core_pattern, "core") || !strcmp(core_pattern, "core.%p"))
diff --git a/tools/testing/selftests/powerpc/utils.c b/tools/testing/selftests/powerpc/utils.c
index 1f36ee1a909a..22ba13425b2c 100644
--- a/tools/testing/selftests/powerpc/utils.c
+++ b/tools/testing/selftests/powerpc/utils.c
@@ -26,34 +26,83 @@
 
 static char auxv[4096];
 
+int read_file(const char *path, char *buf, size_t count, size_t *len)
+{
+	ssize_t rc;
+	int fd;
+	int err;
+	char eof;
+
+	fd = open(path, O_RDONLY);
+	if (fd < 0)
+		return -errno;
+
+	rc = read(fd, buf, count);
+	if (rc < 0) {
+		err = -errno;
+		goto out;
+	}
+
+	if (len)
+		*len = rc;
+
+	/* Overflow if there are still more bytes after filling the buffer */
+	if (rc == count) {
+		rc = read(fd, &eof, 1);
+		if (rc != 0) {
+			err = -EOVERFLOW;
+			goto out;
+		}
+	}
+
+	err = 0;
+
+out:
+	close(fd);
+	errno = -err;
+	return err;
+}
+
+int write_file(const char *path, const char *buf, size_t count)
+{
+	int fd;
+	int err;
+	ssize_t rc;
+
+	fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+	if (fd < 0)
+		return -errno;
+
+	rc = write(fd, buf, count);
+	if (rc < 0) {
+		err = -errno;
+		goto out;
+	}
+
+	if (rc != count) {
+		err = -EOVERFLOW;
+		goto out;
+	}
+
+	err = 0;
+
+out:
+	close(fd);
+	errno = -err;
+	return err;
+}
+
 int read_auxv(char *buf, ssize_t buf_size)
 {
-	ssize_t num;
-	int rc, fd;
+	int err;
 
-	fd = open("/proc/self/auxv", O_RDONLY);
-	if (fd == -1) {
-		perror("open");
-		return -errno;
+	err = read_file("/proc/self/auxv", buf, buf_size, NULL);
+	if (err) {
+		perror("Error reading /proc/self/auxv");
+		return err;
 	}
 
-	num = read(fd, buf, buf_size);
-	if (num < 0) {
-		perror("read");
-		rc = -EIO;
-		goto out;
-	}
-
-	if (num > buf_size) {
-		printf("overflowed auxv buffer\n");
-		rc = -EOVERFLOW;
-		goto out;
-	}
-
-	rc = 0;
-out:
-	close(fd);
-	return rc;
+	return 0;
 }
 
 void *find_auxv_entry(int type, char *auxv)
@@ -142,65 +191,41 @@ bool is_ppc64le(void)
 int read_sysfs_file(char *fpath, char *result, size_t result_size)
 {
 	char path[PATH_MAX] = "/sys/";
-	int rc = -1, fd;
 
 	strncat(path, fpath, PATH_MAX - strlen(path) - 1);
 
-	if ((fd = open(path, O_RDONLY)) < 0)
-		return rc;
-
-	rc = read(fd, result, result_size);
-
-	close(fd);
-
-	if (rc < 0)
-		return rc;
-
-	return 0;
+	return read_file(path, result, result_size, NULL);
 }
 
 int read_debugfs_file(char *debugfs_file, int *result)
 {
-	int rc = -1, fd;
+	int err;
 	char path[PATH_MAX];
-	char value[16];
+	char value[16] = {0};
 
 	strcpy(path, "/sys/kernel/debug/");
 	strncat(path, debugfs_file, PATH_MAX - strlen(path) - 1);
 
-	if ((fd = open(path, O_RDONLY)) < 0)
-		return rc;
+	err = read_file(path, value, sizeof(value) - 1, NULL);
+	if (err)
+		return err;
 
-	if ((rc = read(fd, value, sizeof(value))) < 0)
-		return rc;
-
-	value[15] = 0;
 	*result = atoi(value);
-	close(fd);
 
 	return 0;
 }
 
 int write_debugfs_file(char *debugfs_file, int result)
 {
-	int rc = -1, fd;
 	char path[PATH_MAX];
 	char value[16];
 
 	strcpy(path, "/sys/kernel/debug/");
 	strncat(path, debugfs_file, PATH_MAX - strlen(path) - 1);
 
-	if ((fd = open(path, O_WRONLY)) < 0)
-		return rc;
-
 	snprintf(value, 16, "%d", result);
 
-	if ((rc = write(fd, value, strlen(value))) < 0)
-		return rc;
-
-	close(fd);
-
-	return 0;
+	return write_file(path, value, strlen(value));
 }
 
 static long perf_event_open(struct perf_event_attr *hw_event, pid_t pid,
-- 
2.39.1

[PATCH 2/5] selftests/powerpc: Add read/write debugfs file, int

[Benjamin Gray]

Debugfs files are not always integers, so make *_file return/write a
byte buffer, and *_int deal with int values specifically. This increases
consistency with the other file read/write helpers.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>

---

v4:	* Add reviewed-by
---
 .../testing/selftests/powerpc/include/utils.h |  6 ++--
 .../selftests/powerpc/security/entry_flush.c  | 12 +++----
 .../selftests/powerpc/security/rfi_flush.c    | 12 +++----
 .../powerpc/security/uaccess_flush.c          | 18 +++++-----
 tools/testing/selftests/powerpc/utils.c       | 34 ++++++++++++-------
 5 files changed, 47 insertions(+), 35 deletions(-)

diff --git a/tools/testing/selftests/powerpc/include/utils.h b/tools/testing/selftests/powerpc/include/utils.h
index 70885e5814a8..de5e3790f397 100644
--- a/tools/testing/selftests/powerpc/include/utils.h
+++ b/tools/testing/selftests/powerpc/include/utils.h
@@ -35,8 +35,10 @@ int pick_online_cpu(void);
 
 int read_file(const char *path, char *buf, size_t count, size_t *len);
 int write_file(const char *path, const char *buf, size_t count);
-int read_debugfs_file(char *debugfs_file, int *result);
-int write_debugfs_file(char *debugfs_file, int result);
+int read_debugfs_file(const char *debugfs_file, char *buf, size_t count);
+int write_debugfs_file(const char *debugfs_file, const char *buf, size_t count);
+int read_debugfs_int(const char *debugfs_file, int *result);
+int write_debugfs_int(const char *debugfs_file, int result);
 int read_sysfs_file(char *debugfs_file, char *result, size_t result_size);
 int perf_event_open_counter(unsigned int type,
 			    unsigned long config, int group_fd);
diff --git a/tools/testing/selftests/powerpc/security/entry_flush.c b/tools/testing/selftests/powerpc/security/entry_flush.c
index 68ce377b205e..e01c573deadd 100644
--- a/tools/testing/selftests/powerpc/security/entry_flush.c
+++ b/tools/testing/selftests/powerpc/security/entry_flush.c
@@ -34,18 +34,18 @@ int entry_flush_test(void)
 	// The PMU event we use only works on Power7 or later
 	SKIP_IF(!have_hwcap(PPC_FEATURE_ARCH_2_06));
 
-	if (read_debugfs_file("powerpc/rfi_flush", &rfi_flush_orig) < 0) {
+	if (read_debugfs_int("powerpc/rfi_flush", &rfi_flush_orig) < 0) {
 		perror("Unable to read powerpc/rfi_flush debugfs file");
 		SKIP_IF(1);
 	}
 
-	if (read_debugfs_file("powerpc/entry_flush", &entry_flush_orig) < 0) {
+	if (read_debugfs_int("powerpc/entry_flush", &entry_flush_orig) < 0) {
 		perror("Unable to read powerpc/entry_flush debugfs file");
 		SKIP_IF(1);
 	}
 
 	if (rfi_flush_orig != 0) {
-		if (write_debugfs_file("powerpc/rfi_flush", 0) < 0) {
+		if (write_debugfs_int("powerpc/rfi_flush", 0) < 0) {
 			perror("error writing to powerpc/rfi_flush debugfs file");
 			FAIL_IF(1);
 		}
@@ -105,7 +105,7 @@ int entry_flush_test(void)
 
 	if (entry_flush == entry_flush_orig) {
 		entry_flush = !entry_flush_orig;
-		if (write_debugfs_file("powerpc/entry_flush", entry_flush) < 0) {
+		if (write_debugfs_int("powerpc/entry_flush", entry_flush) < 0) {
 			perror("error writing to powerpc/entry_flush debugfs file");
 			return 1;
 		}
@@ -120,12 +120,12 @@ int entry_flush_test(void)
 
 	set_dscr(0);
 
-	if (write_debugfs_file("powerpc/rfi_flush", rfi_flush_orig) < 0) {
+	if (write_debugfs_int("powerpc/rfi_flush", rfi_flush_orig) < 0) {
 		perror("unable to restore original value of powerpc/rfi_flush debugfs file");
 		return 1;
 	}
 
-	if (write_debugfs_file("powerpc/entry_flush", entry_flush_orig) < 0) {
+	if (write_debugfs_int("powerpc/entry_flush", entry_flush_orig) < 0) {
 		perror("unable to restore original value of powerpc/entry_flush debugfs file");
 		return 1;
 	}
diff --git a/tools/testing/selftests/powerpc/security/rfi_flush.c b/tools/testing/selftests/powerpc/security/rfi_flush.c
index f73484a6470f..6bedc86443a6 100644
--- a/tools/testing/selftests/powerpc/security/rfi_flush.c
+++ b/tools/testing/selftests/powerpc/security/rfi_flush.c
@@ -34,18 +34,18 @@ int rfi_flush_test(void)
 	// The PMU event we use only works on Power7 or later
 	SKIP_IF(!have_hwcap(PPC_FEATURE_ARCH_2_06));
 
-	if (read_debugfs_file("powerpc/rfi_flush", &rfi_flush_orig) < 0) {
+	if (read_debugfs_int("powerpc/rfi_flush", &rfi_flush_orig) < 0) {
 		perror("Unable to read powerpc/rfi_flush debugfs file");
 		SKIP_IF(1);
 	}
 
-	if (read_debugfs_file("powerpc/entry_flush", &entry_flush_orig) < 0) {
+	if (read_debugfs_int("powerpc/entry_flush", &entry_flush_orig) < 0) {
 		have_entry_flush = 0;
 	} else {
 		have_entry_flush = 1;
 
 		if (entry_flush_orig != 0) {
-			if (write_debugfs_file("powerpc/entry_flush", 0) < 0) {
+			if (write_debugfs_int("powerpc/entry_flush", 0) < 0) {
 				perror("error writing to powerpc/entry_flush debugfs file");
 				return 1;
 			}
@@ -105,7 +105,7 @@ int rfi_flush_test(void)
 
 	if (rfi_flush == rfi_flush_orig) {
 		rfi_flush = !rfi_flush_orig;
-		if (write_debugfs_file("powerpc/rfi_flush", rfi_flush) < 0) {
+		if (write_debugfs_int("powerpc/rfi_flush", rfi_flush) < 0) {
 			perror("error writing to powerpc/rfi_flush debugfs file");
 			return 1;
 		}
@@ -120,13 +120,13 @@ int rfi_flush_test(void)
 
 	set_dscr(0);
 
-	if (write_debugfs_file("powerpc/rfi_flush", rfi_flush_orig) < 0) {
+	if (write_debugfs_int("powerpc/rfi_flush", rfi_flush_orig) < 0) {
 		perror("unable to restore original value of powerpc/rfi_flush debugfs file");
 		return 1;
 	}
 
 	if (have_entry_flush) {
-		if (write_debugfs_file("powerpc/entry_flush", entry_flush_orig) < 0) {
+		if (write_debugfs_int("powerpc/entry_flush", entry_flush_orig) < 0) {
 			perror("unable to restore original value of powerpc/entry_flush "
 			       "debugfs file");
 			return 1;
diff --git a/tools/testing/selftests/powerpc/security/uaccess_flush.c b/tools/testing/selftests/powerpc/security/uaccess_flush.c
index cf80f960e38a..fcf23ea9b183 100644
--- a/tools/testing/selftests/powerpc/security/uaccess_flush.c
+++ b/tools/testing/selftests/powerpc/security/uaccess_flush.c
@@ -36,30 +36,30 @@ int uaccess_flush_test(void)
 	// The PMU event we use only works on Power7 or later
 	SKIP_IF(!have_hwcap(PPC_FEATURE_ARCH_2_06));
 
-	if (read_debugfs_file("powerpc/rfi_flush", &rfi_flush_orig) < 0) {
+	if (read_debugfs_int("powerpc/rfi_flush", &rfi_flush_orig) < 0) {
 		perror("Unable to read powerpc/rfi_flush debugfs file");
 		SKIP_IF(1);
 	}
 
-	if (read_debugfs_file("powerpc/entry_flush", &entry_flush_orig) < 0) {
+	if (read_debugfs_int("powerpc/entry_flush", &entry_flush_orig) < 0) {
 		perror("Unable to read powerpc/entry_flush debugfs file");
 		SKIP_IF(1);
 	}
 
-	if (read_debugfs_file("powerpc/uaccess_flush", &uaccess_flush_orig) < 0) {
+	if (read_debugfs_int("powerpc/uaccess_flush", &uaccess_flush_orig) < 0) {
 		perror("Unable to read powerpc/entry_flush debugfs file");
 		SKIP_IF(1);
 	}
 
 	if (rfi_flush_orig != 0) {
-		if (write_debugfs_file("powerpc/rfi_flush", 0) < 0) {
+		if (write_debugfs_int("powerpc/rfi_flush", 0) < 0) {
 			perror("error writing to powerpc/rfi_flush debugfs file");
 			FAIL_IF(1);
 		}
 	}
 
 	if (entry_flush_orig != 0) {
-		if (write_debugfs_file("powerpc/entry_flush", 0) < 0) {
+		if (write_debugfs_int("powerpc/entry_flush", 0) < 0) {
 			perror("error writing to powerpc/entry_flush debugfs file");
 			FAIL_IF(1);
 		}
@@ -119,7 +119,7 @@ int uaccess_flush_test(void)
 
 	if (uaccess_flush == uaccess_flush_orig) {
 		uaccess_flush = !uaccess_flush_orig;
-		if (write_debugfs_file("powerpc/uaccess_flush", uaccess_flush) < 0) {
+		if (write_debugfs_int("powerpc/uaccess_flush", uaccess_flush) < 0) {
 			perror("error writing to powerpc/uaccess_flush debugfs file");
 			return 1;
 		}
@@ -134,17 +134,17 @@ int uaccess_flush_test(void)
 
 	set_dscr(0);
 
-	if (write_debugfs_file("powerpc/rfi_flush", rfi_flush_orig) < 0) {
+	if (write_debugfs_int("powerpc/rfi_flush", rfi_flush_orig) < 0) {
 		perror("unable to restore original value of powerpc/rfi_flush debugfs file");
 		return 1;
 	}
 
-	if (write_debugfs_file("powerpc/entry_flush", entry_flush_orig) < 0) {
+	if (write_debugfs_int("powerpc/entry_flush", entry_flush_orig) < 0) {
 		perror("unable to restore original value of powerpc/entry_flush debugfs file");
 		return 1;
 	}
 
-	if (write_debugfs_file("powerpc/uaccess_flush", uaccess_flush_orig) < 0) {
+	if (write_debugfs_int("powerpc/uaccess_flush", uaccess_flush_orig) < 0) {
 		perror("unable to restore original value of powerpc/uaccess_flush debugfs file");
 		return 1;
 	}
diff --git a/tools/testing/selftests/powerpc/utils.c b/tools/testing/selftests/powerpc/utils.c
index 22ba13425b2c..495299a79f50 100644
--- a/tools/testing/selftests/powerpc/utils.c
+++ b/tools/testing/selftests/powerpc/utils.c
@@ -105,6 +105,24 @@ int read_auxv(char *buf, ssize_t buf_size)
 	return 0;
 }
 
+int read_debugfs_file(const char *subpath, char *buf, size_t count)
+{
+	char path[PATH_MAX] = "/sys/kernel/debug/";
+
+	strncat(path, subpath, sizeof(path) - strlen(path) - 1);
+
+	return read_file(path, buf, count, NULL);
+}
+
+int write_debugfs_file(const char *subpath, const char *buf, size_t count)
+{
+	char path[PATH_MAX] = "/sys/kernel/debug/";
+
+	strncat(path, subpath, sizeof(path) - strlen(path) - 1);
+
+	return write_file(path, buf, count);
+}
+
 void *find_auxv_entry(int type, char *auxv)
 {
 	ElfW(auxv_t) *p;
@@ -197,16 +215,12 @@ int read_sysfs_file(char *fpath, char *result, size_t result_size)
 	return read_file(path, result, result_size, NULL);
 }
 
-int read_debugfs_file(char *debugfs_file, int *result)
+int read_debugfs_int(const char *debugfs_file, int *result)
 {
 	int err;
-	char path[PATH_MAX];
 	char value[16] = {0};
 
-	strcpy(path, "/sys/kernel/debug/");
-	strncat(path, debugfs_file, PATH_MAX - strlen(path) - 1);
-
-	err = read_file(path, value, sizeof(value) - 1, NULL);
+	err = read_debugfs_file(debugfs_file, value, sizeof(value) - 1);
 	if (err)
 		return err;
 
@@ -215,17 +229,13 @@ int read_debugfs_file(char *debugfs_file, int *result)
 	return 0;
 }
 
-int write_debugfs_file(char *debugfs_file, int result)
+int write_debugfs_int(const char *debugfs_file, int result)
 {
-	char path[PATH_MAX];
 	char value[16];
 
-	strcpy(path, "/sys/kernel/debug/");
-	strncat(path, debugfs_file, PATH_MAX - strlen(path) - 1);
-
 	snprintf(value, 16, "%d", result);
 
-	return write_file(path, value, strlen(value));
+	return write_debugfs_file(debugfs_file, value, strlen(value));
 }
 
 static long perf_event_open(struct perf_event_attr *hw_event, pid_t pid,
-- 
2.39.1

[PATCH 3/5] selftests/powerpc: Parse long/unsigned long value safely

[Benjamin Gray]

Often a file is expected to hold an integral value. Existing functions
will use a C stdlib function like atoi or strtol to parse the file.
These operations are error prone, with complicated error conditions
(atoi returns 0 if not a number, and is undefined behaviour if not in
range. strtol returns 0 if not a number, and LONG_MIN/MAX if not in
range + sets errno to ERANGE).

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>

---

v4:	* Implement as C functions, remove macros
	* Declare parsers for intmax_t, uintmax_t
	* Stop validating the remaining buffer after a null terminator
	* Set errno to match the return code
---
 .../testing/selftests/powerpc/include/utils.h |   7 +
 tools/testing/selftests/powerpc/pmu/lib.c     |   6 +-
 tools/testing/selftests/powerpc/utils.c       | 126 +++++++++++++++++-
 3 files changed, 132 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/powerpc/include/utils.h b/tools/testing/selftests/powerpc/include/utils.h
index de5e3790f397..7c1fa385824c 100644
--- a/tools/testing/selftests/powerpc/include/utils.h
+++ b/tools/testing/selftests/powerpc/include/utils.h
@@ -33,6 +33,13 @@ void *get_auxv_entry(int type);
 
 int pick_online_cpu(void);
 
+int parse_intmax(const char *buffer, size_t count, intmax_t *result, int base);
+int parse_uintmax(const char *buffer, size_t count, uintmax_t *result, int base);
+int parse_int(const char *buffer, size_t count, int *result, int base);
+int parse_uint(const char *buffer, size_t count, unsigned int *result, int base);
+int parse_long(const char *buffer, size_t count, long *result, int base);
+int parse_ulong(const char *buffer, size_t count, unsigned long *result, int base);
+
 int read_file(const char *path, char *buf, size_t count, size_t *len);
 int write_file(const char *path, const char *buf, size_t count);
 int read_debugfs_file(const char *debugfs_file, char *buf, size_t count);
diff --git a/tools/testing/selftests/powerpc/pmu/lib.c b/tools/testing/selftests/powerpc/pmu/lib.c
index 960915304a65..1cfc13a25aee 100644
--- a/tools/testing/selftests/powerpc/pmu/lib.c
+++ b/tools/testing/selftests/powerpc/pmu/lib.c
@@ -192,7 +192,6 @@ bool require_paranoia_below(int level)
 {
 	int err;
 	long current;
-	char *end;
 	char buf[16] = {0};
 
 	err = read_file(PARANOID_PATH, buf, sizeof(buf) - 1, NULL);
@@ -201,9 +200,8 @@ bool require_paranoia_below(int level)
 		return false;
 	}
 
-	current = strtol(buf, &end, 10);
-
-	if (end == buf) {
+	err = parse_long(buf, sizeof(buf), &current, 10);
+	if (err) {
 		printf("Couldn't parse " PARANOID_PATH "?\n");
 		return false;
 	}
diff --git a/tools/testing/selftests/powerpc/utils.c b/tools/testing/selftests/powerpc/utils.c
index 495299a79f50..ddfd871881bf 100644
--- a/tools/testing/selftests/powerpc/utils.c
+++ b/tools/testing/selftests/powerpc/utils.c
@@ -8,6 +8,8 @@
 #include <elf.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
 #include <link.h>
 #include <sched.h>
 #include <stdio.h>
@@ -123,6 +125,126 @@ int write_debugfs_file(const char *subpath, const char *buf, size_t count)
 	return write_file(path, buf, count);
 }
 
+static int validate_int_parse(const char *buffer, size_t count, char *end)
+{
+	int err = 0;
+
+	/* Require at least one digit */
+	if (end == buffer) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	/* Require all remaining characters be whitespace-ish */
+	for (; end < buffer + count; end++) {
+		if (*end == '\0')
+			break;
+
+		if (*end != ' ' && *end != '\n') {
+			err = -EINVAL;
+			goto out;
+		}
+	}
+
+out:
+	errno = -err;
+	return err;
+}
+
+static int parse_bounded_int(const char *buffer, size_t count, intmax_t *result,
+			     int base, intmax_t min, intmax_t max)
+{
+	int err;
+	char *end;
+
+	errno = 0;
+	*result = strtoimax(buffer, &end, base);
+
+	if (errno)
+		return -errno;
+
+	err = validate_int_parse(buffer, count, end);
+	if (err)
+		goto out;
+
+	if (*result < min || *result > max)
+		err = -EOVERFLOW;
+
+out:
+	errno = -err;
+	return err;
+}
+
+static int parse_bounded_uint(const char *buffer, size_t count, uintmax_t *result,
+			      int base, uintmax_t max)
+{
+	int err = 0;
+	char *end;
+
+	errno = 0;
+	*result = strtoumax(buffer, &end, base);
+
+	if (errno)
+		return -errno;
+
+	err = validate_int_parse(buffer, count, end);
+	if (err)
+		goto out;
+
+	if (*result > max)
+		err = -EOVERFLOW;
+
+out:
+	errno = -err;
+	return err;
+}
+
+int parse_intmax(const char *buffer, size_t count, intmax_t *result, int base)
+{
+	return parse_bounded_int(buffer, count, result, base, INTMAX_MIN, INTMAX_MAX);
+}
+
+int parse_uintmax(const char *buffer, size_t count, uintmax_t *result, int base)
+{
+	return parse_bounded_uint(buffer, count, result, base, UINTMAX_MAX);
+}
+
+int parse_int(const char *buffer, size_t count, int *result, int base)
+{
+	intmax_t parsed;
+	int err = parse_bounded_int(buffer, count, &parsed, base, INT_MIN, INT_MAX);
+
+	*result = parsed;
+	return err;
+}
+
+int parse_uint(const char *buffer, size_t count, unsigned int *result, int base)
+{
+	uintmax_t parsed;
+	int err = parse_bounded_uint(buffer, count, &parsed, base, UINT_MAX);
+
+	*result = parsed;
+	return err;
+}
+
+int parse_long(const char *buffer, size_t count, long *result, int base)
+{
+	intmax_t parsed;
+	int err = parse_bounded_int(buffer, count, &parsed, base, LONG_MIN, LONG_MAX);
+
+	*result = parsed;
+	return err;
+}
+
+int parse_ulong(const char *buffer, size_t count, unsigned long *result, int base)
+{
+	uintmax_t parsed;
+	int err = parse_bounded_uint(buffer, count, &parsed, base, ULONG_MAX);
+
+	*result = parsed;
+	return err;
+}
+
 void *find_auxv_entry(int type, char *auxv)
 {
 	ElfW(auxv_t) *p;
@@ -224,9 +346,7 @@ int read_debugfs_int(const char *debugfs_file, int *result)
 	if (err)
 		return err;
 
-	*result = atoi(value);
-
-	return 0;
+	return parse_int(value, sizeof(value), result, 10);
 }
 
 int write_debugfs_int(const char *debugfs_file, int result)
-- 
2.39.1

[PATCH 4/5] selftests/powerpc: Add {read,write}_{long,ulong}

[Benjamin Gray]

Add helper functions to read and write (unsigned) long values directly
from/to files. One of the kernel interfaces uses hex strings, so we need
to allow passing a base too.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>

---

v4:	* Set errno where it isn't already set
---
 tools/testing/selftests/powerpc/dscr/dscr.h   |  9 +--
 .../selftests/powerpc/dscr/dscr_sysfs_test.c  | 14 ++--
 .../testing/selftests/powerpc/include/utils.h |  4 +
 tools/testing/selftests/powerpc/pmu/lib.c     |  9 +--
 tools/testing/selftests/powerpc/utils.c       | 81 +++++++++++++++++++
 5 files changed, 95 insertions(+), 22 deletions(-)

diff --git a/tools/testing/selftests/powerpc/dscr/dscr.h b/tools/testing/selftests/powerpc/dscr/dscr.h
index aaa2b0d89f7e..2c54998d4715 100644
--- a/tools/testing/selftests/powerpc/dscr/dscr.h
+++ b/tools/testing/selftests/powerpc/dscr/dscr.h
@@ -65,26 +65,21 @@ inline void set_dscr_usr(unsigned long val)
 unsigned long get_default_dscr(void)
 {
 	int err;
-	char buf[16] = {0};
 	unsigned long val;
 
-	err = read_file(DSCR_DEFAULT, buf, sizeof(buf) - 1, NULL);
+	err = read_ulong(DSCR_DEFAULT, &val, 16);
 	if (err) {
 		perror("read() failed");
 		exit(1);
 	}
-	sscanf(buf, "%lx", &val);
 	return val;
 }
 
 void set_default_dscr(unsigned long val)
 {
 	int err;
-	char buf[16];
 
-	sprintf(buf, "%lx\n", val);
-
-	err = write_file(DSCR_DEFAULT, buf, strlen(buf));
+	err = write_ulong(DSCR_DEFAULT, val, 16);
 	if (err) {
 		perror("write() failed");
 		exit(1);
diff --git a/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c b/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
index c350f193830a..4f1fef6198fc 100644
--- a/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
+++ b/tools/testing/selftests/powerpc/dscr/dscr_sysfs_test.c
@@ -12,16 +12,16 @@
 
 static int check_cpu_dscr_default(char *file, unsigned long val)
 {
-	char buf[10] = {0};
-	int rc;
+	unsigned long cpu_dscr;
+	int err;
 
-	rc = read_file(file, buf, sizeof(buf) - 1, NULL);
-	if (rc)
-		return rc;
+	err = read_ulong(file, &cpu_dscr, 16);
+	if (err)
+		return err;
 
-	if (strtol(buf, NULL, 16) != val) {
+	if (cpu_dscr != val) {
 		printf("DSCR match failed: %ld (system) %ld (cpu)\n",
-					val, strtol(buf, NULL, 16));
+					val, cpu_dscr);
 		return 1;
 	}
 	return 0;
diff --git a/tools/testing/selftests/powerpc/include/utils.h b/tools/testing/selftests/powerpc/include/utils.h
index 7c1fa385824c..311ddc124ebc 100644
--- a/tools/testing/selftests/powerpc/include/utils.h
+++ b/tools/testing/selftests/powerpc/include/utils.h
@@ -42,6 +42,10 @@ int parse_ulong(const char *buffer, size_t count, unsigned long *result, int bas
 
 int read_file(const char *path, char *buf, size_t count, size_t *len);
 int write_file(const char *path, const char *buf, size_t count);
+int read_long(const char *path, long *result, int base);
+int write_long(const char *path, long result, int base);
+int read_ulong(const char *path, unsigned long *result, int base);
+int write_ulong(const char *path, unsigned long result, int base);
 int read_debugfs_file(const char *debugfs_file, char *buf, size_t count);
 int write_debugfs_file(const char *debugfs_file, const char *buf, size_t count);
 int read_debugfs_int(const char *debugfs_file, int *result);
diff --git a/tools/testing/selftests/powerpc/pmu/lib.c b/tools/testing/selftests/powerpc/pmu/lib.c
index 1cfc13a25aee..719f94f10d41 100644
--- a/tools/testing/selftests/powerpc/pmu/lib.c
+++ b/tools/testing/selftests/powerpc/pmu/lib.c
@@ -192,15 +192,8 @@ bool require_paranoia_below(int level)
 {
 	int err;
 	long current;
-	char buf[16] = {0};
 
-	err = read_file(PARANOID_PATH, buf, sizeof(buf) - 1, NULL);
-	if (err) {
-		printf("Couldn't read " PARANOID_PATH "?\n");
-		return false;
-	}
-
-	err = parse_long(buf, sizeof(buf), &current, 10);
+	err = read_long(PARANOID_PATH, &current, 10);
 	if (err) {
 		printf("Couldn't parse " PARANOID_PATH "?\n");
 		return false;
diff --git a/tools/testing/selftests/powerpc/utils.c b/tools/testing/selftests/powerpc/utils.c
index ddfd871881bf..1017f1738619 100644
--- a/tools/testing/selftests/powerpc/utils.c
+++ b/tools/testing/selftests/powerpc/utils.c
@@ -245,6 +245,87 @@ int parse_ulong(const char *buffer, size_t count, unsigned long *result, int bas
 	return err;
 }
 
+int read_long(const char *path, long *result, int base)
+{
+	int err;
+	char buffer[32] = {0};
+
+	err = read_file(path, buffer, sizeof(buffer) - 1, NULL);
+	if (err)
+		return err;
+
+	return parse_long(buffer, sizeof(buffer), result, base);
+}
+
+int read_ulong(const char *path, unsigned long *result, int base)
+{
+	int err;
+	char buffer[32] = {0};
+
+	err = read_file(path, buffer, sizeof(buffer) - 1, NULL);
+	if (err)
+		return err;
+
+	return parse_ulong(buffer, sizeof(buffer), result, base);
+}
+
+int write_long(const char *path, long result, int base)
+{
+	int err;
+	int len;
+	char buffer[32];
+
+	/* Decimal only for now: no format specifier for signed hex values */
+	if (base != 10) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	len = snprintf(buffer, sizeof(buffer), "%ld", result);
+	if (len < 0 || len >= sizeof(buffer)) {
+		err = -EOVERFLOW;
+		goto out;
+	}
+
+	err = write_file(path, buffer, len);
+
+out:
+	errno = -err;
+	return err;
+}
+
+int write_ulong(const char *path, unsigned long result, int base)
+{
+	int err;
+	int len;
+	char buffer[32];
+	char *fmt;
+
+	switch (base) {
+	case 10:
+		fmt = "%lu";
+		break;
+	case 16:
+		fmt = "%lx";
+		break;
+	default:
+		err = -EINVAL;
+		goto out;
+	}
+
+	len = snprintf(buffer, sizeof(buffer), fmt, result);
+	if (len < 0 || len >= sizeof(buffer)) {
+		err = -errno;
+		goto out;
+	}
+
+	err = write_file(path, buffer, len);
+
+out:
+	errno = -err;
+	return err;
+}
+
 void *find_auxv_entry(int type, char *auxv)
 {
 	ElfW(auxv_t) *p;
-- 
2.39.1

[PATCH 5/5] selftests/powerpc: Add automatically allocating read_file

[Benjamin Gray]

A couple of tests roll their own auto-allocating file read logic.

Add a generic implementation and convert them to use it.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>

---

v4:	* Make allocation more concise using realloc(NULL, length)
	  without special casing initial malloc(length)
---
 .../testing/selftests/powerpc/include/utils.h |  1 +
 .../selftests/powerpc/nx-gzip/gzfht_test.c    | 38 +--------
 .../selftests/powerpc/syscalls/Makefile       |  2 +-
 .../selftests/powerpc/syscalls/rtas_filter.c  | 81 +++----------------
 tools/testing/selftests/powerpc/utils.c       | 58 +++++++++++++
 5 files changed, 71 insertions(+), 109 deletions(-)

diff --git a/tools/testing/selftests/powerpc/include/utils.h b/tools/testing/selftests/powerpc/include/utils.h
index 311ddc124ebc..eed7dd7582b2 100644
--- a/tools/testing/selftests/powerpc/include/utils.h
+++ b/tools/testing/selftests/powerpc/include/utils.h
@@ -42,6 +42,7 @@ int parse_ulong(const char *buffer, size_t count, unsigned long *result, int bas
 
 int read_file(const char *path, char *buf, size_t count, size_t *len);
 int write_file(const char *path, const char *buf, size_t count);
+int read_file_alloc(const char *path, char **buf, size_t *len);
 int read_long(const char *path, long *result, int base);
 int write_long(const char *path, long result, int base);
 int read_ulong(const char *path, unsigned long *result, int base);
diff --git a/tools/testing/selftests/powerpc/nx-gzip/gzfht_test.c b/tools/testing/selftests/powerpc/nx-gzip/gzfht_test.c
index fbc3d265155b..4de079923ccb 100644
--- a/tools/testing/selftests/powerpc/nx-gzip/gzfht_test.c
+++ b/tools/testing/selftests/powerpc/nx-gzip/gzfht_test.c
@@ -143,42 +143,6 @@ int gzip_header_blank(char *buf)
 	return i;
 }
 
-/* Caller must free the allocated buffer return nonzero on error. */
-int read_alloc_input_file(char *fname, char **buf, size_t *bufsize)
-{
-	int err;
-	struct stat statbuf;
-	char *p;
-	size_t num_bytes;
-
-	if (stat(fname, &statbuf)) {
-		perror(fname);
-		return -1;
-	}
-
-	assert(NULL != (p = (char *) malloc(statbuf.st_size)));
-
-	err = read_file(fname, p, statbuf.st_size, &num_bytes);
-	if (err) {
-		perror(fname);
-		goto fail;
-	}
-
-	if (num_bytes != statbuf.st_size) {
-		fprintf(stderr, "Actual bytes != expected bytes\n");
-		err = -1;
-		goto fail;
-	}
-
-	*buf = p;
-	*bufsize = num_bytes;
-	return 0;
-
-fail:
-	free(p);
-	return err;
-}
-
 /*
  * Z_SYNC_FLUSH as described in zlib.h.
  * Returns number of appended bytes
@@ -245,7 +209,7 @@ int compress_file(int argc, char **argv, void *handle)
 		fprintf(stderr, "usage: %s <fname>\n", argv[0]);
 		exit(-1);
 	}
-	if (read_alloc_input_file(argv[1], &inbuf, &inlen))
+	if (read_file_alloc(argv[1], &inbuf, &inlen))
 		exit(-1);
 	fprintf(stderr, "file %s read, %ld bytes\n", argv[1], inlen);
 
diff --git a/tools/testing/selftests/powerpc/syscalls/Makefile b/tools/testing/selftests/powerpc/syscalls/Makefile
index b63f8459c704..54ff5cfffc63 100644
--- a/tools/testing/selftests/powerpc/syscalls/Makefile
+++ b/tools/testing/selftests/powerpc/syscalls/Makefile
@@ -6,4 +6,4 @@ CFLAGS += -I../../../../../usr/include
 top_srcdir = ../../../../..
 include ../../lib.mk
 
-$(TEST_GEN_PROGS): ../harness.c
+$(TEST_GEN_PROGS): ../harness.c ../utils.c
diff --git a/tools/testing/selftests/powerpc/syscalls/rtas_filter.c b/tools/testing/selftests/powerpc/syscalls/rtas_filter.c
index 03b487f18d00..9b17780f0b18 100644
--- a/tools/testing/selftests/powerpc/syscalls/rtas_filter.c
+++ b/tools/testing/selftests/powerpc/syscalls/rtas_filter.c
@@ -8,6 +8,7 @@
 #include <byteswap.h>
 #include <stdint.h>
 #include <inttypes.h>
+#include <linux/limits.h>
 #include <stdio.h>
 #include <string.h>
 #include <sys/syscall.h>
@@ -50,70 +51,16 @@ struct region {
 	struct region *next;
 };
 
-int read_entire_file(int fd, char **buf, size_t *len)
-{
-	size_t buf_size = 0;
-	size_t off = 0;
-	int rc;
-
-	*buf = NULL;
-	do {
-		buf_size += BLOCK_SIZE;
-		if (*buf == NULL)
-			*buf = malloc(buf_size);
-		else
-			*buf = realloc(*buf, buf_size);
-
-		if (*buf == NULL)
-			return -ENOMEM;
-
-		rc = read(fd, *buf + off, BLOCK_SIZE);
-		if (rc < 0)
-			return -EIO;
-
-		off += rc;
-	} while (rc == BLOCK_SIZE);
-
-	if (len)
-		*len = off;
-
-	return 0;
-}
-
-static int open_prop_file(const char *prop_path, const char *prop_name, int *fd)
-{
-	char *path;
-	int len;
-
-	/* allocate enough for two string, a slash and trailing NULL */
-	len = strlen(prop_path) + strlen(prop_name) + 1 + 1;
-	path = malloc(len);
-	if (path == NULL)
-		return -ENOMEM;
-
-	snprintf(path, len, "%s/%s", prop_path, prop_name);
-
-	*fd = open(path, O_RDONLY);
-	free(path);
-	if (*fd < 0)
-		return -errno;
-
-	return 0;
-}
-
 static int get_property(const char *prop_path, const char *prop_name,
 			char **prop_val, size_t *prop_len)
 {
-	int rc, fd;
+	char path[PATH_MAX];
 
-	rc = open_prop_file(prop_path, prop_name, &fd);
-	if (rc)
-		return rc;
+	int len = snprintf(path, sizeof(path), "%s/%s", prop_path, prop_name);
+	if (len < 0 || len >= sizeof(path))
+		return -ENOMEM;
 
-	rc = read_entire_file(fd, prop_val, prop_len);
-	close(fd);
-
-	return rc;
+	return read_file_alloc(path, prop_val, prop_len);
 }
 
 int rtas_token(const char *call_name)
@@ -138,22 +85,14 @@ int rtas_token(const char *call_name)
 static int read_kregion_bounds(struct region *kregion)
 {
 	char *buf;
-	int fd;
-	int rc;
+	int err;
 
-	fd = open("/proc/ppc64/rtas/rmo_buffer", O_RDONLY);
-	if (fd < 0) {
-		printf("Could not open rmo_buffer file\n");
+	err = read_file_alloc("/proc/ppc64/rtas/rmo_buffer", &buf, NULL);
+	if (err) {
+		perror("Could not open rmo_buffer file");
 		return RTAS_IO_ASSERT;
 	}
 
-	rc = read_entire_file(fd, &buf, NULL);
-	close(fd);
-	if (rc) {
-		free(buf);
-		return rc;
-	}
-
 	sscanf(buf, "%" SCNx64 " %x", &kregion->addr, &kregion->size);
 	free(buf);
 
diff --git a/tools/testing/selftests/powerpc/utils.c b/tools/testing/selftests/powerpc/utils.c
index 1017f1738619..7c8cfedb012a 100644
--- a/tools/testing/selftests/powerpc/utils.c
+++ b/tools/testing/selftests/powerpc/utils.c
@@ -65,6 +65,64 @@ int read_file(const char *path, char *buf, size_t count, size_t *len)
 	return err;
 }
 
+int read_file_alloc(const char *path, char **buf, size_t *len)
+{
+	size_t read_offset = 0;
+	size_t buffer_len = 0;
+	char *buffer = NULL;
+	int err;
+	int fd;
+
+	fd = open(path, O_RDONLY);
+	if (fd < 0)
+		return -errno;
+
+	/*
+	 * We don't use stat & preallocate st_size because some non-files
+	 * report 0 file size. Instead just dynamically grow the buffer
+	 * as needed.
+	 */
+	while (1) {
+		ssize_t rc;
+
+		if (read_offset >= buffer_len / 2) {
+			char *next_buffer;
+
+			buffer_len = buffer_len ? buffer_len * 2 : 4096;
+			next_buffer = realloc(buffer, buffer_len);
+			if (!next_buffer) {
+				err = -errno;
+				goto out;
+			}
+			buffer = next_buffer;
+		}
+
+		rc = read(fd, buffer + read_offset, buffer_len - read_offset);
+		if (rc < 0) {
+			err = -errno;
+			goto out;
+		}
+
+		if (rc == 0)
+			break;
+
+		read_offset += rc;
+	}
+
+	*buf = buffer;
+	if (len)
+		*len = read_offset;
+
+	err = 0;
+
+out:
+	close(fd);
+	if (err)
+		free(buffer);
+	errno = -err;
+	return err;
+}
+
 int write_file(const char *path, const char *buf, size_t count)
 {
 	int fd;
-- 
2.39.1

Re: [PATCH 0/5] Expand selftest utils

[Michael Ellerman]

On Fri, 3 Feb 2023 11:39:42 +1100, Benjamin Gray wrote:
> Started this when writing tests for a feature I'm working on, needing a way to
> read/write numbers to system files. After writing some utils to safely handle
> file IO and parsing, I realised I'd made the ~6th file read/write implementation
> and only(?) number parser that checks all the failure modes when expecting to
> parse a single number from a file.
> 
> So these utils ended up becoming this series. I also modified some other test
> utils I came across while doing so. My understanding is selftests are not expected
> to be backported, so I wasn't concerned about only introducing new utils and leaving
> the existing implementations be.
> 
> [...]

Applied to powerpc/next.

[1/5] selftests/powerpc: Add generic read/write file util
      https://git.kernel.org/powerpc/c/a974f0c131891027fe8490e654a220151b4caa82
[2/5] selftests/powerpc: Add read/write debugfs file, int
      https://git.kernel.org/powerpc/c/121d340be9a17ed89d523c56203908c01e09a306
[3/5] selftests/powerpc: Parse long/unsigned long value safely
      https://git.kernel.org/powerpc/c/d1bc05b7bf02f8635fe6c445f67d78f85234cbb7
[4/5] selftests/powerpc: Add {read,write}_{long,ulong}
      https://git.kernel.org/powerpc/c/5c20de57888f0962e25a0eeec1a59c98056fc42e
[5/5] selftests/powerpc: Add automatically allocating read_file
      https://git.kernel.org/powerpc/c/8d7253dc447473dfcf3f09fb0fa2bd6f7d05b43b

cheers