vfs_preopen: make use of any hints from samba_path_matching_check_last_component()

samba_path_matching_check_last_component() may return the start and end
offset of a submatch (for us the bytes where the digits are expected).

We use that in order to allow preopen_parse_fname() to just
look at these bytes and ignore any trailing digits after the submatch.

For the current use of samba_path_matching_mswild_create(),
there's no difference as we'll always get replace_start=-1 and
replace_end=-1. But the next commit will make optional use of
samba_path_matching_regex_sub1_create(), which will change the situation
and allow to return hints we got from regexec().

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>

diff --git a/source3/modules/vfs_preopen.c b/source3/modules/vfs_preopen.c
index fa61d36d533a437208aa768927d86edda38f72de..6ee3c059a076a0d856019ba814674aff6d5c9b15 100644 (file)
--- a/source3/modules/vfs_preopen.c
+++ b/source3/modules/vfs_preopen.c
@@ -359,6 +359,7 @@ static struct preopen_state *preopen_state_get(vfs_handle_struct *handle)
 static bool preopen_parse_fname(const char *fname, uint64_t *pnum,
                                size_t *pstart_idx, int *pnum_digits)
 {
+       char digits[PREOPEN_MAX_DIGITS+1] = { 0, };
        const char *p;
        char *q = NULL;
        unsigned long long num;
@@ -366,6 +367,40 @@ static bool preopen_parse_fname(const char *fname, uint64_t *pnum,
        int num_digits = -1;
        int error = 0;
 
+       if (*pstart_idx > 0 && *pnum_digits > 0) {
+               /*
+                * If the caller knowns
+                * how many digits are expected
+                * and on what position,
+                * we should copy the exact
+                * subset before we start
+                * parsing the string into a number
+                */
+
+               if (*pnum_digits < 1) {
+                       /*
+                        * We need at least one digit
+                        */
+                       return false;
+               }
+               if (*pnum_digits > PREOPEN_MAX_DIGITS) {
+                       /*
+                        * a string with as much digits as
+                        * PREOPEN_MAX_DIGITS is the longest
+                        * string that would make any sense for us.
+                        *
+                        * The rest will be checked via
+                        * smb_strtoull().
+                        */
+                       return false;
+               }
+               p = fname + *pstart_idx;
+               memcpy(digits, p, *pnum_digits);
+               p = digits;
+               start_idx = *pstart_idx;
+               goto parse;
+       }
+
        p = strrchr_m(fname, '/');
        if (p == NULL) {
                p = fname;
@@ -385,6 +420,7 @@ static bool preopen_parse_fname(const char *fname, uint64_t *pnum,
 
        start_idx = (p - fname);
 
+parse:
        num = smb_strtoull(p, (char **)&q, 10, &error, SMB_STR_STANDARD);
        if (error != 0) {
                return false;
@@ -397,6 +433,15 @@ static bool preopen_parse_fname(const char *fname, uint64_t *pnum,
 
        num_digits = (q - p);
 
+       if (*pnum_digits != -1 && *pnum_digits != num_digits) {
+               /*
+                * If the caller knowns how many digits
+                * it expects we should fail if we got something
+                * different.
+                */
+               return false;
+       }
+
        *pnum = num;
        *pstart_idx = start_idx;
        *pnum_digits = num_digits;
@@ -446,6 +491,8 @@ static int preopen_openat(struct vfs_handle_struct *handle,
        int new_digits = -1;
        size_t new_end = 0;
        ssize_t match_idx = -1;
+       ssize_t replace_start = -1;
+       ssize_t replace_end = -1;
        bool need_reset = false;
 
        DEBUG(10, ("preopen_open called on %s\n", smb_fname_str_dbg(smb_fname)));
@@ -493,8 +540,8 @@ static int preopen_openat(struct vfs_handle_struct *handle,
        status = samba_path_matching_check_last_component(state->preopen_names,
                                                          smb_fname->base_name,
                                                          &match_idx,
-                                                         NULL, /* replace_start */
-                                                         NULL);/* replace_end */
+                                                         &replace_start,
+                                                         &replace_end);
        if (!NT_STATUS_IS_OK(status)) {
                match_idx = -1;
        }
@@ -511,6 +558,12 @@ static int preopen_openat(struct vfs_handle_struct *handle,
                return res;
        }
 
+       if (replace_start != -1 && replace_end != -1) {
+               size_t dirofs = strlen(dirname) + 1;
+               new_start = dirofs + replace_start;
+               new_digits = replace_end - replace_start;
+       }
+
        if (!preopen_parse_fname(new_template, &num,
                                 &new_start, &new_digits)) {
                TALLOC_FREE(new_template);