[Qemu-devel] [PATCH] suppress 'warn_unused_result' warning

[Chih-Min Chao <cmchao@gmail.com>]

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The patch add error handling to functions with 'warn_unused_result' return
value
such as write, read, ftruncate, and realpath.

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From 61851f65266eaafd4ff8775c097dafd7c2d3a2c3 Mon Sep 17 00:00:00 2001
From: Chih-Mih Chao <cmchao@gmail.com>
Date: Mon, 11 May 2009 02:57:05 +0800
Subject: [PATCH] add error handling to suppress 'warn_unused_result' warning

---
 block-bochs.c     |    3 ++-
 block-cow.c       |   11 +++++++++--
 block-qcow.c      |   17 ++++++++++++++---
 block-qcow2.c     |   38 ++++++++++++++++++++++++++++++--------
 block-raw-posix.c |    5 ++++-
 block-vmdk.c      |   26 +++++++++++++++++++-------
 block-vvfat.c     |    4 +++-
 block.c           |    3 ++-
 qemu-nbd.c        |    3 ++-
 usb-linux.c       |    4 +++-
 vl.c              |   18 ++++++++++++++----
 11 files changed, 102 insertions(+), 30 deletions(-)

diff --git a/block-bochs.c b/block-bochs.c
index 7a75412..97ec528 100644
--- a/block-bochs.c
+++ b/block-bochs.c
@@ -198,7 +198,8 @@ static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
     // read in bitmap for current extent
     lseek(s->fd, bitmap_offset + (extent_offset / 8), SEEK_SET);
 
-    read(s->fd, &bitmap_entry, 1);
+    if (read(s->fd, &bitmap_entry, 1) == -1)
+        return -1;
 
     if (!((bitmap_entry >> (extent_offset % 8)) & 1))
     {
diff --git a/block-cow.c b/block-cow.c
index 17e3292..c0e3911 100644
--- a/block-cow.c
+++ b/block-cow.c
@@ -239,11 +239,18 @@ static int cow_create(const char *filename, int64_t image_sectors,
     }
     cow_header.sectorsize = cpu_to_be32(512);
     cow_header.size = cpu_to_be64(image_sectors * 512);
-    write(cow_fd, &cow_header, sizeof(cow_header));
+    if (write(cow_fd, &cow_header, sizeof(cow_header)) == -1)
+        goto fail;
     /* resize to include at least all the bitmap */
-    ftruncate(cow_fd, sizeof(cow_header) + ((image_sectors + 7) >> 3));
+    if (ftruncate(cow_fd, sizeof(cow_header) + ((image_sectors + 7) >> 3)) == -1)
+        goto fail;
+
     close(cow_fd);
     return 0;
+
+fail:
+    close(cow_fd);
+    return -1;
 }
 
 static void cow_flush(BlockDriverState *bs)
diff --git a/block-qcow.c b/block-qcow.c
index fc6b809..16138f3 100644
--- a/block-qcow.c
+++ b/block-qcow.c
@@ -811,17 +811,28 @@ static int qcow_create(const char *filename, int64_t total_size,
     }
 
     /* write all the data */
-    write(fd, &header, sizeof(header));
+    if (write(fd, &header, sizeof(header)) == -1) {
+        goto fail;
+    }
+
     if (backing_file) {
-        write(fd, backing_file, backing_filename_len);
+        if (write(fd, backing_file, backing_filename_len) == -1) {
+            goto fail;
+        }
     }
     lseek(fd, header_size, SEEK_SET);
     tmp = 0;
     for(i = 0;i < l1_size; i++) {
-        write(fd, &tmp, sizeof(tmp));
+        if (write(fd, &tmp, sizeof(tmp)) == -1) {
+            goto fail;
+        }
     }
     close(fd);
     return 0;
+
+fail:
+    close(fd);
+    return -1;
 }
 
 static int qcow_make_empty(BlockDriverState *bs)
diff --git a/block-qcow2.c b/block-qcow2.c
index 9a49777..1306f42 100644
--- a/block-qcow2.c
+++ b/block-qcow2.c
@@ -1662,7 +1662,9 @@ static int qcow_create2(const char *filename, int64_t total_size,
     create_refcount_update(s, s->refcount_block_offset, ref_clusters * s->cluster_size);
 
     /* write all the data */
-    write(fd, &header, sizeof(header));
+    if (write(fd, &header, sizeof(header)) == -1) {
+        goto fail;
+    }
     if (backing_file) {
         if (backing_format_len) {
             char zero[16];
@@ -1671,29 +1673,49 @@ static int qcow_create2(const char *filename, int64_t total_size,
             memset(zero, 0, sizeof(zero));
             cpu_to_be32s(&ext_bf.magic);
             cpu_to_be32s(&ext_bf.len);
-            write(fd, &ext_bf, sizeof(ext_bf));
-            write(fd, backing_format, backing_format_len);
+            if (write(fd, &ext_bf, sizeof(ext_bf)) == -1) {
+                goto fail;
+            }
+            if (write(fd, backing_format, backing_format_len) == -1) {
+                goto fail;
+            }
             if (d>0) {
-                write(fd, zero, d);
+                if (write(fd, zero, d) == -1) {
+                    goto fail;
+                }
             }
         }
-        write(fd, backing_file, backing_filename_len);
+        if (write(fd, backing_file, backing_filename_len) == -1) {
+	    goto fail;
+	}
     }
     lseek(fd, s->l1_table_offset, SEEK_SET);
     tmp = 0;
     for(i = 0;i < l1_size; i++) {
-        write(fd, &tmp, sizeof(tmp));
+        if (write(fd, &tmp, sizeof(tmp)) == -1) {
+            goto fail;
+        }
     }
     lseek(fd, s->refcount_table_offset, SEEK_SET);
-    write(fd, s->refcount_table, s->cluster_size);
+    if (write(fd, s->refcount_table, s->cluster_size) == -1) {
+        goto fail;
+    }
 
     lseek(fd, s->refcount_block_offset, SEEK_SET);
-    write(fd, s->refcount_block, ref_clusters * s->cluster_size);
+    if (write(fd, s->refcount_block, ref_clusters * s->cluster_size) == -1) {
+        goto fail;
+    }
 
     qemu_free(s->refcount_table);
     qemu_free(s->refcount_block);
     close(fd);
     return 0;
+
+fail:
+    qemu_free(s->refcount_table);
+    qemu_free(s->refcount_block);
+    close(fd);
+    return -1;
 }
 
 static int qcow_create(const char *filename, int64_t total_size,
diff --git a/block-raw-posix.c b/block-raw-posix.c
index 0663c06..3ace450 100644
--- a/block-raw-posix.c
+++ b/block-raw-posix.c
@@ -835,7 +835,10 @@ static int raw_create(const char *filename, int64_t total_size,
               0644);
     if (fd < 0)
         return -EIO;
-    ftruncate(fd, total_size * 512);
+    if (ftruncate(fd, total_size * 512) < 0) {
+        close(fd);
+        return -EIO;
+    }
     close(fd);
     return 0;
 }
diff --git a/block-vmdk.c b/block-vmdk.c
index d47d483..b880377 100644
--- a/block-vmdk.c
+++ b/block-vmdk.c
@@ -232,7 +232,8 @@ static int vmdk_snapshot_create(const char *filename, const char *backing_file)
     memset(&header, 0, sizeof(header));
     memcpy(&header,&hdr[4], sizeof(header)); // skip the VMDK4_MAGIC
 
-    ftruncate(snp_fd, header.grain_offset << 9);
+    if (ftruncate(snp_fd, header.grain_offset << 9) == -1)
+        goto fail;
     /* the descriptor offset = 0x200 */
     if (lseek(p_fd, 0x200, SEEK_SET) == -1)
         goto fail;
@@ -756,22 +757,28 @@ static int vmdk_create(const char *filename, int64_t total_size,
     header.check_bytes[3] = 0xa;
 
     /* write all the data */
-    write(fd, &magic, sizeof(magic));
-    write(fd, &header, sizeof(header));
+    if (write(fd, &magic, sizeof(magic)) == -1)
+        goto fail;
+    if (write(fd, &header, sizeof(header)) == -1)
+        goto fail;
 
-    ftruncate(fd, header.grain_offset << 9);
+    if (ftruncate(fd, header.grain_offset << 9) == -1)
+        goto fail;
 
     /* write grain directory */
     lseek(fd, le64_to_cpu(header.rgd_offset) << 9, SEEK_SET);
     for (i = 0, tmp = header.rgd_offset + gd_size;
          i < gt_count; i++, tmp += gt_size)
-        write(fd, &tmp, sizeof(tmp));
+        if (write(fd, &tmp, sizeof(tmp)) == -1)
+            goto fail;
 
     /* write backup grain directory */
     lseek(fd, le64_to_cpu(header.gd_offset) << 9, SEEK_SET);
     for (i = 0, tmp = header.gd_offset + gd_size;
          i < gt_count; i++, tmp += gt_size)
-        write(fd, &tmp, sizeof(tmp));
+        if (write(fd, &tmp, sizeof(tmp)) == -1)
+            goto fail;
+
 
     /* compose the descriptor */
     real_filename = filename;
@@ -788,10 +795,15 @@ static int vmdk_create(const char *filename, int64_t total_size,
 
     /* write the descriptor */
     lseek(fd, le64_to_cpu(header.desc_offset) << 9, SEEK_SET);
-    write(fd, desc, strlen(desc));
+    if (write(fd, desc, strlen(desc)) == -1)
+        goto fail;
 
     close(fd);
     return 0;
+
+    fail:
+    close(fd);
+    return -1;
 }
 
 static void vmdk_close(BlockDriverState *bs)
diff --git a/block-vvfat.c b/block-vvfat.c
index 7905931..4de09ff 100644
--- a/block-vvfat.c
+++ b/block-vvfat.c
@@ -2256,7 +2256,9 @@ static int commit_one_file(BDRVVVFATState* s,
 	c = c1;
     }
 
-    ftruncate(fd, size);
+    if (ftruncate(fd, size) < 0)
+        return -4;
+
     close(fd);
 
     return commit_mappings(s, first_cluster, dir_index);
diff --git a/block.c b/block.c
index acb8976..55c64c6 100644
--- a/block.c
+++ b/block.c
@@ -394,7 +394,8 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags,
             snprintf(backing_filename, sizeof(backing_filename),
                      "%s", filename);
         else
-            realpath(filename, backing_filename);
+            if (realpath(filename, backing_filename) == NULL)
+                return -1;
 
         ret = bdrv_create2(&bdrv_qcow2, tmp_filename,
                            total_size, backing_filename, 
diff --git a/qemu-nbd.c b/qemu-nbd.c
index 0af97ca..b60602d 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -346,7 +346,8 @@ int main(int argc, char **argv)
         int sock;
 
         if (!verbose)
-            daemon(0, 0);	/* detach client and server */
+            if (daemon(0, 0) == -1)	/* detach client and server */
+                errx(errno, "Could not run in background");
 
         if (socket == NULL) {
             sprintf(sockpath, SOCKET_PATH, basename(device));
diff --git a/usb-linux.c b/usb-linux.c
index 70d7a1c..98e55b1 100644
--- a/usb-linux.c
+++ b/usb-linux.c
@@ -1160,7 +1160,9 @@ static int usb_host_read_file(char *line, size_t line_size, const char *device_f
              device_file);
     f = fopen(filename, "r");
     if (f) {
-        fgets(line, line_size, f);
+        if (fgets(line, line_size, f) == NULL)
+            monitor_printf(mon, "husb: could not read %s\n", filename);
+
         fclose(f);
         ret = 1;
     } else {
diff --git a/vl.c b/vl.c
index 8e4fba6..7e88ee1 100644
--- a/vl.c
+++ b/vl.c
@@ -3696,7 +3696,8 @@ static void qemu_event_increment(void)
     if (io_thread_fd == -1)
         return;
 
-    write(io_thread_fd, &byte, sizeof(byte));
+    if (write(io_thread_fd, &byte, sizeof(byte)) == -1)
+        perror("Failed write io_thread");
 }
 
 static void qemu_event_read(void *opaque)
@@ -5629,7 +5630,8 @@ int main(int argc, char **argv, char **envp)
     if (pid_file && qemu_create_pidfile(pid_file) != 0) {
         if (daemonize) {
             uint8_t status = 1;
-            write(fds[1], &status, 1);
+            if (write(fds[1], &status, 1) == -1)
+                fprintf(stderr, "Could not write status\n");
         } else
             fprintf(stderr, "Could not acquire pid file\n");
         exit(1);
@@ -6047,7 +6049,11 @@ int main(int argc, char **argv, char **envp)
 	if (len != 1)
 	    exit(1);
 
-	chdir("/");
+	if (chdir("/") == -1) {
+            fprintf(stderr, "change directory to '/' failed");
+            exit(1);
+        }
+
 	TFR(fd = open("/dev/null", O_RDWR));
 	if (fd == -1)
 	    exit(1);
@@ -6066,7 +6072,11 @@ int main(int argc, char **argv, char **envp)
             fprintf(stderr, "chroot failed\n");
             exit(1);
         }
-        chdir("/");
+
+	if (chdir("/") == -1) {
+            fprintf(stderr, "change directory to '/' failed");
+            exit(1);
+        }
     }
 
     if (run_as) {
-- 
1.6.0.4