Check return value of fwrite when copying files

Check that writing to destination file actually occurs in
_alpm_copyfile.  Required adding a new error (PM_ERR_WRITE)
as none of the others appeared appropriate.

Prevents compiler warning when using -D_FORTIFY_SOURCE=2.

Signed-off-by: Allan McRae <allan@archlinux.org>
Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 9 insertions, 1 deletions

diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c
index b033e0a3..fd5bb628 100644
--- a/lib/libalpm/util.c
+++ b/lib/libalpm/util.c
@@ -143,7 +143,15 @@ int _alpm_copyfile(const char *src, const char *dest)
 
 	/* do the actual file copy */
 	while((len = fread(buf, 1, CPBUFSIZE, in))) {
-		fwrite(buf, 1, len, out);
+		size_t nwritten = 0;
+		nwritten = fwrite(buf, 1, len, out);
+		if((nwritten != len) || ferror(out)) {
+			pm_errno = PM_ERR_WRITE;
+			_alpm_log(PM_LOG_ERROR, _("error writing to file '%s': %s\n"),
+					dest, strerror(errno));
+			ret = -1;
+			goto cleanup;
+		}
 	}
 
 	/* chmod dest to permissions of src, as long as it is not a symlink */