[Qemu-devel] [PATCH 1/3] curl: Fix parsing of readahead option from filename

[Matthew Booth]

curl_parse_filename wasn't removing the option string from the url,
resulting in a 404.

This change is a essentially a rewrite of that function as I also need
to extend it to handle more options. The rewrite is also much easier
to read.

Signed-off-by: Matthew Booth <address@hidden>
---
 block/curl.c | 59 +++++++++++++++++++++++++++++++++++++----------------------
 1 file changed, 37 insertions(+), 22 deletions(-)

diff --git a/block/curl.c b/block/curl.c
index d2f1084..2a03924 100644
--- a/block/curl.c
+++ b/block/curl.c
@@ -396,38 +396,53 @@ static void curl_clean_state(CURLState *s)
 static void curl_parse_filename(const char *filename, QDict *options,
                                 Error **errp)
 {
+    #define READAHEAD "readahead"
 
-    #define RA_OPTSTR ":readahead="
     char *file;
-    char *ra;
-    const char *ra_val;
-    int parse_state = 0;
+    char *end;
 
     file = g_strdup(filename);
+    end = file + strlen(file) - 1;
 
-    /* Parse a trailing ":readahead=#:" param, if present. */
-    ra = file + strlen(file) - 1;
-    while (ra >= file) {
-        if (parse_state == 0) {
-            if (*ra == ':') {
-                parse_state++;
-            } else {
+    /* Don't fail if we've been passed an empty string. Only examine strings
+     * with a trailing ':' */
+    if (end >= file && *end == ':') {
+        /* We exit this loop when we don't find a recognised option immediately
+         * preceding the trailing ':' of the form ':<option>=<value>'
+         *
+         * If filename has a trailing ':' but no preceding options, we don't
+         * remove the trailing ':'.
+         */
+        for (;;) {
+            /* Look for the preceding colon */
+            char *colon = memrchr(file, ':', end - file);
+            if (NULL == colon) {
                 break;
             }
-        } else if (parse_state == 1) {
-            if (*ra > '9' || *ra < '0') {
-                char *opt_start = ra - strlen(RA_OPTSTR) + 1;
-                if (opt_start > file &&
-                    strncmp(opt_start, RA_OPTSTR, strlen(RA_OPTSTR)) == 0) {
-                    ra_val = ra + 1;
-                    ra -= strlen(RA_OPTSTR) - 1;
-                    *ra = '\0';
-                    qdict_put(options, "readahead", qstring_from_str(ra_val));
-                }
+
+            char *opt_start = colon + 1;
+
+            /* Look for an equals sign */
+            char *equals = memchr(opt_start, '=', end - opt_start);
+            if (NULL == equals) {
                 break;
             }
+
+            char *value = equals + 1;
+
+            if (memcmp(opt_start, READAHEAD, equals - opt_start) == 0) {
+                /* This is redundant after the first iteration */
+                *end = '\0';
+                qdict_put(options, READAHEAD, qstring_from_str(value));
+            } else {
+                break;
+            }
+
+            end = colon;
+
+            /* We've found at least 1 option. Remove the trailing ':' */
+            *end = '\0';
         }
-        ra--;
     }
 
     qdict_put(options, "url", qstring_from_str(file));
-- 
1.9.0