Date: Mon, 4 Aug 2003 02:33:31 +0200 From: Simon Barner <barner@in.tum.de> To: Terry Lambert <tlambert2@mindspring.com> Cc: kientzle@acm.org Subject: Re: [patch] Re: getfsent(3) and spaces in fstab Message-ID: <20030804003331.GA408@zi025.glhnet.mhn.de> In-Reply-To: <3F2B75E2.FBC18052@mindspring.com> References: <20030730224505.GD531@zi025.glhnet.mhn.de> <1059607242.64020.5.camel@mjtdev1.dand06.au.bytecraft.au.com> <3F285560.2090607@acm.org> <1059608748.64020.10.camel@mjtdev1.dand06.au.bytecraft.au.com> <002201c356fa$4a66a700$1200a8c0@gsicomp.on.ca> <20030731134343.GB1323@zi025.glhnet.mhn.de> <1059693358.64020.31.camel@mjtdev1.dand06.au.bytecraft.au.com> <20030801153142.GA487@zi025.glhnet.mhn.de> <3F2B75E2.FBC18052@mindspring.com>
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Hi Terry,
> You need to add '\\' to the list of characters that can be escaped,
> or you've just traded the inability to specify '\t' or ' ' for an
> inability to speciy '\\'.
Oh yes, I have overlook this special case. I revised my patch in order
to get this right.
Simon
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--- fstab.c.orig Fri Aug 1 17:18:00 2003
+++ fstab.c Mon Aug 4 01:46:55 2003
@@ -49,6 +49,7 @@
#include <errno.h>
#include <fstab.h>
#include <paths.h>
+#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@@ -84,6 +85,140 @@
_fs_fstab.fs_spec =3D buf;
}
=20
+/*
+ * Get next token from string *stringp, where tokens are possibly-empty
+ * strings separated by characters from delim.
+ *
+ * Writes NULs into the string at *stringp to end tokens.
+ * delim need not remain constant from call to call.
+ * On return, *stringp points past the last NUL written (if there might
+ * be further tokens), or is NULL (if there are definitely no more tokens).
+ *
+ * If *stringp is NULL, es_strsep returns NULL.
+ *
+ * In contrast to strsep(3), es_strsep will allow escaped delimiters
+ * within a token. These escaped characters as well as the special case
+ * '\\' will be converted appropriately ('\<delim>' -> '<delim>, '\\' -> '=
\'
+ *
+ */
+char *
+es_strsep(char **stringp, const char *delim)
+{
+ bool escaped=3Dfalse;
+ char *s, *t, *u;
+ int i;
+
+
+ if (*stringp =3D=3D '\0') /* empty string */
+ return NULL;
+ s =3D *stringp;
+ s +=3D strspn (s, delim); /* skip delimiters */
+
+ if (*s =3D=3D '\0') /* string consists only of delimiters */
+ return NULL;
+=09
+ /*
+ * skip a string consisting of non-delimiters,
+ * escapted delimiters or '\\'
+ */
+ for (t =3D s; *t !=3D '\0'; ++t) {
+ if (*t =3D=3D '\\') {
+ if (escaped) { /* convert \\ to \ */
+ --t;
+ u =3D t;
+ escaped =3D false;
+ while (u[0] !=3D '\0') {
+ u[0] =3D u[1];
+ ++u;
+ }
+ } else /* start \-Sequence */
+ escaped =3D true;
+ continue;
+ }
+ =09
+ /* search for delimiter */
+ for (i=3D0; delim[i] !=3D '\0'; ++i) {
+ if (*t =3D=3D delim[i])
+ break;
+ }
+ =09
+ /* un-escaped delimiter found =3D> end of token */
+ if (!escaped && delim[i] !=3D '\0')
+ break;
+ =20
+ /* escaped delimiter found =3D> remove / */
+ if (escaped) {
+ --t;
+ u =3D t;
+ escaped =3D false;
+ while (u[0] !=3D '\0') {
+ u[0] =3D u[1];
+ ++u;
+ }
+ }
+ }
+
+ if (*t !=3D '\0') {
+ *t =3D '\0'; /* end current token */
+ *stringp =3D t+1; /* *t !=3D '\0' =3D> *(t+1) is valid */
+ } else
+ *stringp =3D 0; /* end of string reached */=09
+=09
+ return s; /* return current token */
+}
+
+/*
+ * This function converts escaped characters:
+ * '\<delim>' -> '<delim>', '\\' -> '\'
+ *=20
+ * If there are unescaped delimiters, 'false' will be return to indicate
+ * an error, otherwise remove_escape returns 'true'.
+ */
+bool remove_escapes (char **s, const char* delim) {
+ bool escaped=3Dfalse;
+ char *t, *u;
+ int i;
+=09
+ for (t =3D *s; *t !=3D '\0'; ++t) {
+ if (*t =3D=3D '\\') {
+ if (escaped) { /* convert \\ to \ */
+ --t;
+ u =3D t;
+ escaped =3D false;
+ while (u[0] !=3D '\0') {
+ u[0] =3D u[1];
+ ++u;
+ }
+ } else /* start \-Sequence */
+ escaped =3D true;
+ continue;
+ }
+ =09
+ /* search for delimiter */
+ for (i=3D0; delim[i] !=3D '\0'; ++i) {
+ if (*t =3D=3D delim[i])
+ break;
+ }
+ =09
+ /* un-escaped delimiter found =3D> error */
+ if (!escaped && delim[i] !=3D '\0')
+ return false;
+
+ /* escaped delimiter found =3D> remove / */
+ if (escaped) {
+ --t;
+ u =3D t;
+ escaped =3D false;
+ while (u[0] !=3D '\0') {
+ u[0] =3D u[1];
+ ++u;
+ }
+ }
+ }
+=09
+ return true;
+}
+
static int
fstabscan()
{
@@ -101,9 +236,19 @@
++LineNo;
if (*line =3D=3D '#' || *line =3D=3D '\n')
continue;
- if (!strpbrk(p, " \t")) {
+
+ /* escapted white-spaces only are allowed in old-style format */
+ cp =3D p;
+ while ((cp =3D strpbrk(cp, " \t")) !=3D 0 &&
+ cp !=3D p && cp[-1] =3D=3D '\\')
+ ++cp;
+ if (cp =3D=3D 0) {
_fs_fstab.fs_spec =3D strsep(&p, ":\n");
+ if (!remove_escapes (&_fs_fstab.fs_spec, " \t"))
+ goto bad;
_fs_fstab.fs_file =3D strsep(&p, ":\n");
+ if (!remove_escapes (&_fs_fstab.fs_file, " \t"))
+ goto bad;
fixfsfile();
_fs_fstab.fs_type =3D strsep(&p, ":\n");
if (_fs_fstab.fs_type) {
@@ -124,13 +269,15 @@
goto bad;
}
/* OLD_STYLE_FSTAB */
- while ((cp =3D strsep(&p, " \t\n")) !=3D NULL && *cp =3D=3D '\0')
+ while ((cp =3D es_strsep(&p, " \t\n")) !=3D NULL && *cp =3D=3D '\0')
;
_fs_fstab.fs_spec =3D cp;
if (!_fs_fstab.fs_spec || *_fs_fstab.fs_spec =3D=3D '#')
continue;
- while ((cp =3D strsep(&p, " \t\n")) !=3D NULL && *cp =3D=3D '\0')
+ while ((cp =3D es_strsep(&p, " \t\n")) !=3D NULL && *cp =3D=3D '\0')
;
+ if (cp =3D=3D 0)
+ goto bad;
_fs_fstab.fs_file =3D cp;
fixfsfile();
while ((cp =3D strsep(&p, " \t\n")) !=3D NULL && *cp =3D=3D '\0')
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