win32: special treatment for PATH

The PATH shell variable is a special case.  It can be exported to
the environment where it might be interpreted by native applications
which assume the separator is ';'.  Hence:

- require that the separator used in PATH is ';'
- enforce this by intercepting calls to setvareq() that set PATH
  and adjusting its value if necessary.

As a result of this the code to parse PATH can be simplified by
replacing the hardcoded Unix ':' path separator by the platform-
dependent macro PATH_SEP.

The MANPATH variable is also required to use ';' as its separator
but since it's less likely to be used this isn't enforced.

1 files changed, 61 insertions, 25 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 3bbfbd694..a659fd703 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -2422,6 +2422,42 @@ bltinlookup(const char *name)
         return lookupvar(name);
 }
 
+#if ENABLE_PLATFORM_MINGW32
+static char *
+fix_pathvar(const char *path)
+{
+        char *newpath = xstrdup(path);
+        char *p;
+        int modified = FALSE;
+
+        p = newpath + 5;
+        while (*p) {
+                if (*p != ':' && *p != ';') {
+                        /* skip drive */
+                        if (isalpha(*p) && p[1] == ':')
+                                p += 2;
+                        /* skip through path component */
+                        for (; *p != '\0' && *p != ':' && *p != ';'; ++p)
+                                continue;
+                }
+                /* *p is ':', ';' or '\0' here */
+                if (*p == ':') {
+                        *p++ = ';';
+                        modified = TRUE;
+                }
+                else if (*p == ';') {
+                        ++p;
+                }
+        }
+
+        if (!modified) {
+                free(newpath);
+                newpath = NULL;
+        }
+        return newpath;
+}
+#endif
+
 /*
  * Same as setvar except that the variable and value are passed in
  * the first argument as name=value.  Since the first argument will
@@ -2434,6 +2470,19 @@ setvareq(char *s, int flags)
 {
         struct var *vp, **vpp;
 
+#if ENABLE_PLATFORM_MINGW32
+        if (strncmp(s, "PATH=", 5) == 0) {
+                char *newpath = fix_pathvar(s);
+                if (newpath) {
+                        if ((flags & (VTEXTFIXED|VSTACK|VNOSAVE)) == VNOSAVE)
+                                free(s);
+                        flags |= VNOSAVE;
+                        flags &= ~(VTEXTFIXED|VSTACK);
+                        s = newpath;
+                }
+        }
+#endif
+
         vpp = hashvar(s);
         flags |= (VEXPORT & (((unsigned) (1 - aflag)) - 1));
         vpp = findvar(vpp, s);
@@ -2646,18 +2695,8 @@ path_advance(const char **path, const char *name)
         if (*path == NULL)
                 return NULL;
         start = *path;
-#if ENABLE_PLATFORM_MINGW32
-        p = next_path_sep(start);
-        q = strchr(start, '%');
-        if ((p && q && q < p) || (!p && q))
-                p = q;
-        if (!p)
-                for (p = start; *p; p++)
-                        continue;
-#else
-        for (p = start; *p && *p != ':' && *p != '%'; p++)
+        for (p = start; *p && *p != PATH_SEP && *p != '%'; p++)
                 continue;
-#endif
         len = p - start + strlen(name) + 2;     /* "2" is for '/' and '\0' */
 
         /* reserve space for suffix on WIN32 */
@@ -2672,19 +2711,10 @@ path_advance(const char **path, const char *name)
         pathopt = NULL;
         if (*p == '%') {
                 pathopt = ++p;
-#if ENABLE_PLATFORM_MINGW32
-                p = next_path_sep(start);
-
-                /* *p != ':' and '*' would suffice */
-                if (!p)
-                        p = pathopt - 1;
-#else
-                while (*p && *p != ':')
+                while (*p && *p != PATH_SEP)
                         p++;
-#endif
         }
-        if (*p == ':' ||
-            (ENABLE_PLATFORM_MINGW32 && *p == ';'))
+        if (*p == PATH_SEP)
                 *path = p + 1;
         else
                 *path = NULL;
@@ -8733,8 +8763,8 @@ changepath(const char *new)
         for (;;) {
                 if (*old != *new) {
                         firstchange = idx;
-                        if ((*old == '\0' && *new == ':')
-                         || (*old == ':' && *new == '\0')
+                        if ((*old == '\0' && *new == PATH_SEP)
+                         || (*old == PATH_SEP && *new == '\0')
                         ) {
                                 firstchange++;
                         }
@@ -8744,7 +8774,7 @@ changepath(const char *new)
                         break;
                 if (*new == '%' && idx_bltin < 0 && prefix(new + 1, "builtin"))
                         idx_bltin = idx;
-                if (*new == ':')
+                if (*new == PATH_SEP)
                         idx++;
                 new++;
                 old++;
@@ -10585,7 +10615,13 @@ evalcommand(union node *cmd, int flags)
                  */
                 p = (*spp)->text;
                 if (varcmp(p, path) == 0)
+#if !ENABLE_PLATFORM_MINGW32
                         path = p;
+#else
+                        /* fix_pathvar may have modified the value of the local
+                         * variable so we look it up again */
+                        path = vpath.var_text;
+#endif
         }
 
         /* Print the command if xflag is set. */