[PATCH 2/2] entry.c: convert write_entry to use strbuf

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

The strcpy call in open_output_fd() implies that the output buffer
must be at least 25 chars long. And it's true. The only caller that
can trigger that code is checkout-index, which has the buffer of
PATH_MAX chars (and any systems that have PATH_MAX shorter than 25
chars are just insane).

But in order to say that, one has to walk through a dozen of
functions. Just convert it to strbuf to avoid the constraint and
confusion.

Although my original motivation was simpler than that. I just wanted
to change "char *path" to "const char *path" in checkout_entry() to
make sure no funny business regarding "path" in that function.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin/checkout-index.c | 19 ++++++++++++-------
 cache.h                  |  2 +-
 entry.c                  | 29 ++++++++++++++++-------------
 3 files changed, 29 insertions(+), 21 deletions(-)

diff --git a/builtin/checkout-index.c b/builtin/checkout-index.c
index 69e167b..6d88c0c 100644
--- a/builtin/checkout-index.c
+++ b/builtin/checkout-index.c
@@ -14,7 +14,12 @@
 static int line_termination = '\n';
 static int checkout_stage; /* default to checkout stage0 */
 static int to_tempfile;
-static char topath[4][PATH_MAX + 1];
+static struct strbuf topath[4] = {
+	STRBUF_INIT,
+	STRBUF_INIT,
+	STRBUF_INIT,
+	STRBUF_INIT
+};
 
 static struct checkout state;
 
@@ -26,19 +31,19 @@ static void write_tempfile_record(const char *name, int prefix_length)
 		for (i = 1; i < 4; i++) {
 			if (i > 1)
 				putchar(' ');
-			if (topath[i][0])
-				fputs(topath[i], stdout);
+			if (topath[i].len)
+				fputs(topath[i].buf, stdout);
 			else
 				putchar('.');
 		}
 	} else
-		fputs(topath[checkout_stage], stdout);
+		fputs(topath[checkout_stage].buf, stdout);
 
 	putchar('\t');
 	write_name_quoted(name + prefix_length, stdout, line_termination);
 
 	for (i = 0; i < 4; i++) {
-		topath[i][0] = 0;
+		strbuf_reset(&topath[i]);
 	}
 }
 
@@ -65,7 +70,7 @@ static int checkout_file(const char *name, int prefix_length)
 			continue;
 		did_checkout = 1;
 		if (checkout_entry(ce, &state,
-		    to_tempfile ? topath[ce_stage(ce)] : NULL) < 0)
+		    to_tempfile ? &topath[ce_stage(ce)] : NULL) < 0)
 			errs++;
 	}
 
@@ -109,7 +114,7 @@ static void checkout_all(const char *prefix, int prefix_length)
 				write_tempfile_record(last_ce->name, prefix_length);
 		}
 		if (checkout_entry(ce, &state,
-		    to_tempfile ? topath[ce_stage(ce)] : NULL) < 0)
+		    to_tempfile ? &topath[ce_stage(ce)] : NULL) < 0)
 			errs++;
 		last_ce = ce;
 	}
diff --git a/cache.h b/cache.h
index 51d6602..276182f 100644
--- a/cache.h
+++ b/cache.h
@@ -962,7 +962,7 @@ struct checkout {
 		 refresh_cache:1;
 };
 
-extern int checkout_entry(struct cache_entry *ce, const struct checkout *state, char *topath);
+extern int checkout_entry(struct cache_entry *ce, const struct checkout *state, struct strbuf *topath);
 
 struct cache_def {
 	char path[PATH_MAX + 1];
diff --git a/entry.c b/entry.c
index d955af5..a76942d 100644
--- a/entry.c
+++ b/entry.c
@@ -92,15 +92,15 @@ static void *read_blob_entry(const struct cache_entry *ce, unsigned long *size)
 	return NULL;
 }
 
-static int open_output_fd(char *path, const struct cache_entry *ce, int to_tempfile)
+static int open_output_fd(struct strbuf *path, const struct cache_entry *ce, int to_tempfile)
 {
 	int symlink = (ce->ce_mode & S_IFMT) != S_IFREG;
 	if (to_tempfile) {
-		strcpy(path, symlink
-		       ? ".merge_link_XXXXXX" : ".merge_file_XXXXXX");
-		return mkstemp(path);
+		strbuf_reset(path);
+		strbuf_addstr(path, symlink ? ".merge_link_XXXXXX" : ".merge_file_XXXXXX");
+		return mkstemp(path->buf);
 	} else {
-		return create_file(path, !symlink ? ce->ce_mode : 0666);
+		return create_file(path->buf, !symlink ? ce->ce_mode : 0666);
 	}
 }
 
@@ -115,7 +115,7 @@ static int fstat_output(int fd, const struct checkout *state, struct stat *st)
 	return 0;
 }
 
-static int streaming_write_entry(const struct cache_entry *ce, char *path,
+static int streaming_write_entry(const struct cache_entry *ce, struct strbuf *path,
 				 struct stream_filter *filter,
 				 const struct checkout *state, int to_tempfile,
 				 int *fstat_done, struct stat *statbuf)
@@ -132,12 +132,12 @@ static int streaming_write_entry(const struct cache_entry *ce, char *path,
 	result |= close(fd);
 
 	if (result)
-		unlink(path);
+		unlink(path->buf);
 	return result;
 }
 
 static int write_entry(struct cache_entry *ce,
-		       char *path, const struct checkout *state, int to_tempfile)
+		       struct strbuf *path_buf, const struct checkout *state, int to_tempfile)
 {
 	unsigned int ce_mode_s_ifmt = ce->ce_mode & S_IFMT;
 	int fd, ret, fstat_done = 0;
@@ -146,15 +146,17 @@ static int write_entry(struct cache_entry *ce,
 	unsigned long size;
 	size_t wrote, newsize = 0;
 	struct stat st;
+	const char *path;
 
 	if (ce_mode_s_ifmt == S_IFREG) {
 		struct stream_filter *filter = get_stream_filter(ce->name, ce->sha1);
 		if (filter &&
-		    !streaming_write_entry(ce, path, filter,
+		    !streaming_write_entry(ce, path_buf, filter,
 					   state, to_tempfile,
 					   &fstat_done, &st))
 			goto finish;
 	}
+	path = path_buf->buf;
 
 	switch (ce_mode_s_ifmt) {
 	case S_IFREG:
@@ -183,7 +185,8 @@ static int write_entry(struct cache_entry *ce,
 			size = newsize;
 		}
 
-		fd = open_output_fd(path, ce, to_tempfile);
+		fd = open_output_fd(path_buf, ce, to_tempfile);
+		path = path_buf->buf;
 		if (fd < 0) {
 			free(new);
 			return error("unable to create file %s (%s)",
@@ -235,10 +238,10 @@ static int check_path(const char *path, int len, struct stat *st, int skiplen)
 }
 
 int checkout_entry(struct cache_entry *ce,
-		   const struct checkout *state, char *topath)
+		   const struct checkout *state, struct strbuf *topath)
 {
 	static struct strbuf path_buf = STRBUF_INIT;
-	char *path;
+	const char *path;
 	struct stat st;
 	int len;
 
@@ -278,5 +281,5 @@ int checkout_entry(struct cache_entry *ce,
 	} else if (state->not_new)
 		return 0;
 	create_directories(path, len, state);
-	return write_entry(ce, path, state, 0);
+	return write_entry(ce, &path_buf, state, 0);
 }
-- 
1.8.2.83.gc99314b

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