Simplify and fix common prefix calculation

diff --git a/src/nnn.c b/src/nnn.c
index ee162e29e5eaeb5cbae6deb779607c0810361252..5001ba2463ca86a06ea47474e9e02c9ea767c6d4 100644 (file)
--- a/src/nnn.c
+++ b/src/nnn.c
@@ -948,81 +948,46 @@ static void *xmemrchr(uchar *s, uchar ch, size_t n)
 }
 
 /* Assumes both the paths passed are directories */
-static char *common_prefix(const char *s, char *prefix)
+static char *common_prefix(const char *path, char *prefix)
 {
-       if (!s || !*s ||  !prefix)
+       const char *x = path, *y = prefix;
+       char *sep;
+
+       if (!path || !*path || !prefix)
                return NULL;
 
        if (!*prefix) {
-               xstrlcpy(prefix, s, PATH_MAX);
+               xstrlcpy(prefix, path, PATH_MAX);
                return prefix;
        }
 
-       /* Only accept non-empty strings */
-       if (*s == '\0' || *prefix == '\0')
-               return NULL;
-
-       ulong *x, *y;
-       size_t i = 0, j = 0, blocks = 0;
-       size_t len_s = strlen(s), len_prefix = strlen(prefix);
-       size_t len = MIN(len_s, len_prefix);
-       char *tmp;
-
-       /*
-        * To enable -O3 ensure s and prefix are 16-byte aligned
-        * More info: https://www.felixcloutier.com/x86/MOVDQA:VMOVDQA32:VMOVDQA64
-        */
-       if ((len >= LONG_SIZE) && (((ulong)s & _ALIGNMENT_MASK) == 0
-                              && ((ulong)prefix & _ALIGNMENT_MASK) == 0)) {
-               x = (ulong *)s;
-               y = (ulong *)prefix;
-               blocks = len >> _WSHIFT;
-               len &= LONG_SIZE - 1;
-
-               while (i < blocks && (*x == *y))
-                       ++x, ++y, ++i;
-
-               /* This should always return */
-               if (i < blocks) {
-                       i *= LONG_SIZE;
-                       for (; j < LONG_SIZE; ++j)
-                               if (s[i + j] != prefix[i + j]) {
-                                       tmp = xmemrchr((uchar *)prefix, '/', i + j);
-                                       if (!tmp)
-                                               return NULL;
-
-                                       *(tmp != prefix ? tmp : tmp + 1) = '\0';
+       while (*x && *y && (*x == *y))
+               ++x, ++y;
 
-                                       return prefix;
-                               }
-               }
+       /* Strings are same OR prefix is smaller */
+       if ((!*x && !*y) || !*y)
+               return prefix;
 
-               if (!len)
-                       return prefix;
+       /* Path is smaller */
+       if (!*x) {
+               xstrlcpy(prefix, path, path - x + 1);
+               return prefix;
        }
 
-       i = blocks * LONG_SIZE;
-       while (j < len && s[i + j] == prefix[i + j])
-               ++j;
-
-       if (j < len) {
-               tmp = xmemrchr((uchar *)prefix, '/', i + j);
-               if (!tmp)
-                       return NULL;
-
-               *(tmp != prefix ? tmp : tmp + 1) = '\0';
-
+       /* Paths deviate and prefix ends with '/' */
+       if (y != prefix && *y == '/') {
+               prefix[y - prefix] = '\0';
                return prefix;
        }
 
-       /* complete match but lenghts might differ */
-       if (len_s < len_prefix || (len_s > len_prefix && s[len_prefix] != '/')) {
-               tmp = xmemrchr((uchar *)prefix, '/', len);
-               if (!tmp)
-                       return NULL;
+       /* Shorten prefix */
+       prefix[y - prefix] = '\0';
 
-               *(tmp != prefix ? tmp : tmp + 1) = '\0';
-       }
+       sep = xmemrchr((uchar *)prefix, '/', y - prefix);
+       if (sep != prefix)
+               *sep = '\0';
+       else /* Just '/' */
+               prefix[1] = '\0';
 
        return prefix;
 }
@@ -1031,7 +996,7 @@ static char *common_prefix(const char *s, char *prefix)
  * The library function realpath() resolves symlinks.
  * If there's a symlink in file list we want to show the symlink not what it's points to.
  */
-static char *xrealpath(const char *path, const char *cwd)
+static char *abspath(const char *path, const char *cwd)
 {
        if (!path || !cwd)
                return NULL;
@@ -1058,7 +1023,7 @@ static char *xrealpath(const char *path, const char *cwd)
 
                if (next - src == 2 && src[0] == '.' && src[1] == '.') {
                        if (dst - resolved_path) {
-                               dst = xmemrchr((uchar *)resolved_path, '/', dst-resolved_path);
+                               dst = xmemrchr((uchar *)resolved_path, '/', dst - resolved_path);
                                *dst = '\0';
                        }
                } else if (next - src == 1 && src[0] == '.') {
@@ -6259,7 +6224,7 @@ static char *load_input()
                        continue;
                }
 
-               if (!(paths[i] = xrealpath(paths[i], cwd))) {
+               if (!(paths[i] = abspath(paths[i], cwd))) {
                        entries = i; // free from the previous entry
                        goto malloc_2;
 
@@ -6278,15 +6243,17 @@ static char *load_input()
 
        DPRINTF_S(g_prefixpath);
 
-       if (entries == 1) {
-               tmp = xmemrchr((uchar *)g_prefixpath, '/', strlen(g_prefixpath));
-               if (!tmp)
-                       goto malloc_2;
+       if (g_prefixpath[0]) {
+               if (entries == 1) {
+                       tmp = xmemrchr((uchar *)g_prefixpath, '/', strlen(g_prefixpath));
+                       if (!tmp)
+                               goto malloc_2;
 
-               *(tmp != g_prefixpath ? tmp : tmp + 1) = '\0';
-       }
+                       *(tmp != g_prefixpath ? tmp : tmp + 1) = '\0';
+               }
 
-       tmpdir = make_tmp_tree(paths, entries, g_prefixpath);
+               tmpdir = make_tmp_tree(paths, entries, g_prefixpath);
+       }
 
 malloc_2:
        for (i = entries - 1; i >= 0; --i)