Re: PATCH: avoid clobbering errno before err/warn

[Doug Hogan]

On Sat, Jul 19, 2014 at 06:40:54PM -0700, Philip Guenther wrote:
> Nice job!  Committed (except for the microcode/bwi file where your diff
> revealed another existing bug that we can fix at the same time...)

Thanks!  Here's the patch with the existing bug fixed.  I checked other
places for err/warn in this file but I think I'm already touching them
all.


Index: sys/dev/microcode/bwi/build/build.c
===================================================================
RCS file: /cvs/src/sys/dev/microcode/bwi/build/build.c,v
retrieving revision 1.3
diff -u -p -d -r1.3 build.c
--- sys/dev/microcode/bwi/build/build.c 12 Jul 2014 19:01:49 -0000      1.3
+++ sys/dev/microcode/bwi/build/build.c 20 Jul 2014 01:56:52 -0000
@@ -20,6 +20,7 @@
 #include <sys/stat.h>
 
 #include <err.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -104,12 +105,14 @@ main(int argc, char *argv[])
 
        /* write header */
        if (write(fdout, &nfiles, sizeof(nfiles)) < 1) {
+               int saved_errno = errno;
                close(fdout);
-               err(1, "write header 1 to output file failed\n");
+               errc(1, saved_errno, "write header 1 to output file failed");
        }
        if (write(fdout, h, headersize - sizeof(nfiles)) < 1) {
+               int saved_errno = errno;
                close(fdout);
-               err(1, "write header 2 to output file failed\n");
+               errc(1, saved_errno, "write header 2 to output file failed");
        }
 
        /* network to host byte order */
@@ -122,25 +125,29 @@ main(int argc, char *argv[])
        /* write each file */
        for (i = 0; i < nfiles; i++) {
                if ((fdin = open(h[i].filename, O_RDONLY)) == -1) {
+                       int saved_errno = errno;
                        close(fdout);
-                       err(1, "open input file failed\n");
+                       errc(1, saved_errno, "open input file failed");
                }
                if ((p = malloc(h[i].filesize)) == NULL) {
+                       int saved_errno = errno;
                        close(fdout);
                        close(fdin);
-                       err(1, "malloc");
+                       errc(1, saved_errno, "malloc");
                }
                if (read(fdin, p, h[i].filesize) < 1) {
+                       int saved_errno = errno;
                        free(p);
                        close(fdout);
                        close(fdin);
-                       err(1, "read input file failed\n");
+                       errc(1, saved_errno, "read input file failed");
                }
                if (write(fdout, p, h[i].filesize) < 1) {
+                       int saved_errno = errno;
                        free(p);
                        close(fdout);
                        close(fdin);
-                       err(1, "write to output file failed\n");
+                       errc(1, saved_errno, "write to output file failed");
                }
                free(p);
                close(fdin);