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authorStephen Gallagher <sgallagh@redhat.com>2010-06-08 15:47:34 -0400
committerStephen Gallagher <sgallagh@redhat.com>2010-06-10 10:17:38 -0400
commit06247775aa9c49ffce72827921eb45e2d04c6aa1 (patch)
treec3e53abf07faa3c8e161cff30746d54af6a78791 /src/tools
parente5196fd7da44e4ae04ab8b5d2e7191167762cf0b (diff)
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Properly handle read() and write() throughout the SSSD
We need to guarantee at all times that reads and writes complete successfully. This means that they must be checked for returning EINTR and EAGAIN, and all writes must be wrapped in a loop to ensure that they do not truncate their output.
Diffstat (limited to 'src/tools')
-rw-r--r--src/tools/files.c55
1 files changed, 36 insertions, 19 deletions
diff --git a/src/tools/files.c b/src/tools/files.c
index b3b516ea..27ebf72d 100644
--- a/src/tools/files.c
+++ b/src/tools/files.c
@@ -402,7 +402,7 @@ static int copy_file(const char *src,
int ifd = -1;
int ofd = -1;
char buf[1024];
- ssize_t cnt, written, offset;
+ ssize_t cnt, written, res;
struct stat fstatbuf;
ifd = open(src, O_RDONLY);
@@ -454,27 +454,44 @@ static int copy_file(const char *src,
goto fail;
}
- while ((cnt = read(ifd, buf, sizeof(buf))) > 0) {
- offset = 0;
- while (cnt > 0) {
- written = write(ofd, buf+offset, (size_t)cnt);
- if (written == -1) {
- ret = errno;
- DEBUG(1, ("Cannot write() to source file '%s': [%d][%s].\n",
- dst, ret, strerror(ret)));
- goto fail;
+ while ((cnt = read(ifd, buf, sizeof(buf))) != 0) {
+ if (cnt == -1) {
+ if (errno == EINTR || errno == EAGAIN) {
+ continue;
}
- offset += written;
- cnt -= written;
+
+ DEBUG(1, ("Cannot read() from source file '%s': [%d][%s].\n",
+ src, ret, strerror(ret)));
+ goto fail;
+ }
+ else if (cnt > 0) {
+ /* Copy the buffer to the new file */
+ written = 0;
+ while (written < cnt) {
+ res = write(ofd, buf+written, (size_t)cnt-written);
+ if (res == -1) {
+ ret = errno;
+ if (ret == EINTR || ret == EAGAIN) {
+ /* retry the write */
+ continue;
+ }
+ DEBUG(1, ("Cannot write() to destination file '%s': [%d][%s].\n",
+ dst, ret, strerror(ret)));
+ goto fail;
+ }
+ else if (res <= 0) {
+ DEBUG(1, ("Unexpected result from write(): [%d]\n", res));
+ goto fail;
+ }
+
+ written += res;
+ }
+ }
+ else {
+ DEBUG(1, ("Unexpected return code of read [%d]\n", cnt));
+ goto fail;
}
}
- if (cnt == -1) {
- ret = errno;
- DEBUG(1, ("Cannot read() from source file '%s': [%d][%s].\n",
- dst, ret, strerror(ret)));
- goto fail;
- }
-
ret = close(ifd);
ifd = -1;