tools/perf/util/path.c

   1 /*
   2  * I'm tired of doing "vsnprintf()" etc just to open a
   3  * file, so here's a "return static buffer with printf"
   4  * interface for paths.
   5  *
   6  * It's obviously not thread-safe. Sue me. But it's quite
   7  * useful for doing things like
   8  *
   9  *   f = open(mkpath("%s/%s.perf", base, name), O_RDONLY);
  10  *
  11  * which is what it's designed for.
  12  */
  13 #include "cache.h"
  14
  15 static char bad_path[] = "/bad-path/";
  16 /*
  17  * Two hacks:
  18  */
  19
  20 static const char *get_perf_dir(void)
  21 {
  22         return ".";
  23 }
  24
  25 /*
  26  * If libc has strlcpy() then that version will override this
  27  * implementation:
  28  */
  29 size_t __weak strlcpy(char *dest, const char *src, size_t size)
  30 {
  31         size_t ret = strlen(src);
  32
  33         if (size) {
  34                 size_t len = (ret >= size) ? size - 1 : ret;
  35
  36                 memcpy(dest, src, len);
  37                 dest[len] = '\0';
  38         }
  39
  40         return ret;
  41 }
  42
  43 static char *get_pathname(void)
  44 {
  45         static char pathname_array[4][PATH_MAX];
  46         static int idx;
  47
  48         return pathname_array[3 & ++idx];
  49 }
  50
  51 static char *cleanup_path(char *path)
  52 {
  53         /* Clean it up */
  54         if (!memcmp(path, "./", 2)) {
  55                 path += 2;
  56                 while (*path == '/')
  57                         path++;
  58         }
  59         return path;
  60 }
  61
  62 static char *perf_vsnpath(char *buf, size_t n, const char *fmt, va_list args)
  63 {
  64         const char *perf_dir = get_perf_dir();
  65         size_t len;
  66
  67         len = strlen(perf_dir);
  68         if (n < len + 1)
  69                 goto bad;
  70         memcpy(buf, perf_dir, len);
  71         if (len && !is_dir_sep(perf_dir[len-1]))
  72                 buf[len++] = '/';
  73         len += vsnprintf(buf + len, n - len, fmt, args);
  74         if (len >= n)
  75                 goto bad;
  76         return cleanup_path(buf);
  77 bad:
  78         strlcpy(buf, bad_path, n);
  79         return buf;
  80 }
  81
  82 char *perf_pathdup(const char *fmt, ...)
  83 {
  84         char path[PATH_MAX];
  85         va_list args;
  86         va_start(args, fmt);
  87         (void)perf_vsnpath(path, sizeof(path), fmt, args);
  88         va_end(args);
  89         return xstrdup(path);
  90 }
  91
  92 char *mkpath(const char *fmt, ...)
  93 {
  94         va_list args;
  95         unsigned len;
  96         char *pathname = get_pathname();
  97
  98         va_start(args, fmt);
  99         len = vsnprintf(pathname, PATH_MAX, fmt, args);
 100         va_end(args);
 101         if (len >= PATH_MAX)
 102                 return bad_path;
 103         return cleanup_path(pathname);
 104 }
 105
 106 char *perf_path(const char *fmt, ...)
 107 {
 108         const char *perf_dir = get_perf_dir();
 109         char *pathname = get_pathname();
 110         va_list args;
 111         unsigned len;
 112
 113         len = strlen(perf_dir);
 114         if (len > PATH_MAX-100)
 115                 return bad_path;
 116         memcpy(pathname, perf_dir, len);
 117         if (len && perf_dir[len-1] != '/')
 118                 pathname[len++] = '/';
 119         va_start(args, fmt);
 120         len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
 121         va_end(args);
 122         if (len >= PATH_MAX)
 123                 return bad_path;
 124         return cleanup_path(pathname);
 125 }
 126
 127 /* strip arbitrary amount of directory separators at end of path */
 128 static inline int chomp_trailing_dir_sep(const char *path, int len)
 129 {
 130         while (len && is_dir_sep(path[len - 1]))
 131                 len--;
 132         return len;
 133 }
 134
 135 /*
 136  * If path ends with suffix (complete path components), returns the
 137  * part before suffix (sans trailing directory separators).
 138  * Otherwise returns NULL.
 139  */
 140 char *strip_path_suffix(const char *path, const char *suffix)
 141 {
 142         int path_len = strlen(path), suffix_len = strlen(suffix);
 143
 144         while (suffix_len) {
 145                 if (!path_len)
 146                         return NULL;
 147
 148                 if (is_dir_sep(path[path_len - 1])) {
 149                         if (!is_dir_sep(suffix[suffix_len - 1]))
 150                                 return NULL;
 151                         path_len = chomp_trailing_dir_sep(path, path_len);
 152                         suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
 153                 }
 154                 else if (path[--path_len] != suffix[--suffix_len])
 155                         return NULL;
 156         }
 157
 158         if (path_len && !is_dir_sep(path[path_len - 1]))
 159                 return NULL;
 160         return strndup(path, chomp_trailing_dir_sep(path, path_len));
 161 }