[musl] [PATCH] getmntent_r: support empty source field

[Oliver Ford <ojford@gmail.com>]

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Some mount types such as tmpfs allow the source field
to be an empty string. Handle the case of an empty source
field with a second sscanf if the first does not match every field.

Issue originally raised by Keyu Tao on 6th April. As per discussion,
octal escape characters are not yet supported but can be implemented
next.
---
 src/misc/mntent.c | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/src/misc/mntent.c b/src/misc/mntent.c
index eabb8200..43041881 100644
--- a/src/misc/mntent.c
+++ b/src/misc/mntent.c
@@ -21,7 +21,7 @@ int endmntent(FILE *f)

 struct mntent *getmntent_r(FILE *f, struct mntent *mnt, char *linebuf, int
buflen)
 {
- int cnt, n[8], use_internal = (linebuf == SENTINEL);
+ int cnt, ch, n[8], use_internal = (linebuf == SENTINEL);

  mnt->mnt_freq = 0;
  mnt->mnt_passno = 0;
@@ -39,20 +39,38 @@ struct mntent *getmntent_r(FILE *f, struct mntent *mnt,
char *linebuf, int bufle
  errno = ERANGE;
  return 0;
  }
+
+ ch = strspn(linebuf, " ");
+ if (linebuf[ch] == '#') continue;
+
  cnt = sscanf(linebuf, " %n%*s%n %n%*s%n %n%*s%n %n%*s%n %d %d",
  n, n+1, n+2, n+3, n+4, n+5, n+6, n+7,
  &mnt->mnt_freq, &mnt->mnt_passno);
- } while (cnt < 2 || linebuf[n[0]] == '#');
-
- linebuf[n[1]] = 0;
- linebuf[n[3]] = 0;
- linebuf[n[5]] = 0;
- linebuf[n[7]] = 0;
+ if (cnt == 2) {
+ linebuf[n[1]] = 0;
+ linebuf[n[3]] = 0;
+ linebuf[n[5]] = 0;
+ linebuf[n[7]] = 0;
+ mnt->mnt_fsname = linebuf+n[0];
+ mnt->mnt_dir = linebuf+n[2];
+ mnt->mnt_type = linebuf+n[4];
+ mnt->mnt_opts = linebuf+n[6];
+ } else {
+ cnt = sscanf(linebuf, " %n%*s%n %n%*s%n %n%*s%n %d %d",
+ n, n+1, n+2, n+3, n+4, n+5, n+6,
+ &mnt->mnt_freq, &mnt->mnt_passno);

- mnt->mnt_fsname = linebuf+n[0];
- mnt->mnt_dir = linebuf+n[2];
- mnt->mnt_type = linebuf+n[4];
- mnt->mnt_opts = linebuf+n[6];
+ if (cnt == 2) {
+ linebuf[n[1]] = 0;
+ linebuf[n[3]] = 0;
+ linebuf[n[5]] = 0;
+ mnt->mnt_fsname = "";
+ mnt->mnt_dir = linebuf+n[0];
+ mnt->mnt_type = linebuf+n[2];
+ mnt->mnt_opts = linebuf+n[4];
+ }
+ }
+ } while (cnt < 2);

  return mnt;
 }
-- 
2.35.1

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