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* [musl] [PATCH v2] fix: Assign default value to mntent when linebuf is too small
@ 2021-09-27  8:26 Kaihang Zhang
  0 siblings, 0 replies; only message in thread
From: Kaihang Zhang @ 2021-09-27  8:26 UTC (permalink / raw)
  To: 2010267516, musl; +Cc: Kaihang Zhang

Function getmntent_r in source misc/mntent.c will do what glibc users
expect. The rest of the line will be discarded when can not be read
into linebuf, and the fields of struct mntent will be assigned to empty
string or zero when can not be found in linebuf, instead of setting
errno to ERANGE and exiting.
---
 src/misc/mntent.c | 54 +++++++++++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 21 deletions(-)

diff --git a/src/misc/mntent.c b/src/misc/mntent.c
index eabb8200..007c0b8d 100644
--- a/src/misc/mntent.c
+++ b/src/misc/mntent.c
@@ -21,12 +21,12 @@ 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);
-
-	mnt->mnt_freq = 0;
-	mnt->mnt_passno = 0;
+	int use_internal = (linebuf == SENTINEL);
+	char *sub;
 
 	do {
+		char *end_ptr;
+
 		if (use_internal) {
 			getline(&internal_buf, &internal_bufsize, f);
 			linebuf = internal_buf;
@@ -34,25 +34,37 @@ struct mntent *getmntent_r(FILE *f, struct mntent *mnt, char *linebuf, int bufle
 			fgets(linebuf, buflen, f);
 		}
 		if (feof(f) || ferror(f)) return 0;
-		if (!strchr(linebuf, '\n')) {
+
+		end_ptr = strchr(linebuf, '\n');
+		if (end_ptr != NULL) {
+			while ((end_ptr[-1] == ' ' || end_ptr[-1] == '\t') && end_ptr != linebuf) end_ptr--;
+			*end_ptr = '\0';
+		} else {
 			fscanf(f, "%*[^\n]%*[\n]");
-			errno = ERANGE;
-			return 0;
 		}
-		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;
-
-	mnt->mnt_fsname = linebuf+n[0];
-	mnt->mnt_dir = linebuf+n[2];
-	mnt->mnt_type = linebuf+n[4];
-	mnt->mnt_opts = linebuf+n[6];
+
+		linebuf += strspn(linebuf, " \t");
+	} while (linebuf[0] == '\0' || linebuf[0] == '#');
+
+	mnt->mnt_fsname = strsep(&linebuf, " \t");
+
+	if (linebuf) linebuf += strspn(linebuf, " \t");
+	sub = strsep(&linebuf, " \t");
+	mnt->mnt_dir = sub ? sub : (char *) "";
+
+	if (linebuf) linebuf += strspn(linebuf, " \t");
+	sub = strsep (&linebuf, " \t");
+	mnt->mnt_type = sub ? sub : (char *) "";
+
+	if (linebuf) linebuf += strspn(linebuf, " \t");
+	sub = strsep(&linebuf, " \t");
+	mnt->mnt_opts = sub ? sub : (char *) "";
+
+	switch (linebuf ? sscanf(linebuf, " %d %d", &mnt->mnt_freq, &mnt->mnt_passno) : 0) {
+	case 0: mnt->mnt_freq = 0;
+	case 1: mnt->mnt_passno = 0;
+	case 2: break;
+	}
 
 	return mnt;
 }
-- 
2.25.4


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2021-09-27  8:26 [musl] [PATCH v2] fix: Assign default value to mntent when linebuf is too small Kaihang Zhang

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