path.c

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/*
 * I'm tired of doing "vsnprintf()" etc just to open a
 * file, so here's a "return static buffer with printf"
 * interface for paths.
 *
 * It's obviously not thread-safe. Sue me. But it's quite
 * useful for doing things like
 *
 *   f = open(mkpath("%s/%s.perf", base, name), O_RDONLY);
 *
 * which is what it's designed for.
 */
#include "cache.h"

static char bad_path[] = "/bad-path/";
/*
 * Two hacks:
 */

static const char *get_perf_dir(void)
{
    return ".";
}

#ifndef HAVE_STRLCPY
size_t strlcpy(char *dest, const char *src, size_t size)
{
    size_t ret = strlen(src);

    if (size) {
        size_t len = (ret >= size) ? size - 1 : ret;
        memcpy(dest, src, len);
        dest[len] = '\0';
    }
    return ret;
}
#endif

static char *get_pathname(void)
{
    static char pathname_array[4][PATH_MAX];
    static int idx;

    return pathname_array[3 & ++idx];
}

static char *cleanup_path(char *path)
{
    /* Clean it up */
    if (!memcmp(path, "./", 2)) {
        path += 2;
        while (*path == '/')
            path++;
    }
    return path;
}

static char *perf_vsnpath(char *buf, size_t n, const char *fmt, va_list args)
{
    const char *perf_dir = get_perf_dir();
    size_t len;

    len = strlen(perf_dir);
    if (n < len + 1)
        goto bad;
    memcpy(buf, perf_dir, len);
    if (len && !is_dir_sep(perf_dir[len-1]))
        buf[len++] = '/';
    len += vsnprintf(buf + len, n - len, fmt, args);
    if (len >= n)
        goto bad;
    return cleanup_path(buf);
bad:
    strlcpy(buf, bad_path, n);
    return buf;
}

char *perf_pathdup(const char *fmt, ...)
{
    char path[PATH_MAX];
    va_list args;
    va_start(args, fmt);
    (void)perf_vsnpath(path, sizeof(path), fmt, args);
    va_end(args);
    return xstrdup(path);
}

char *mkpath(const char *fmt, ...)
{
    va_list args;
    unsigned len;
    char *pathname = get_pathname();

    va_start(args, fmt);
    len = vsnprintf(pathname, PATH_MAX, fmt, args);
    va_end(args);
    if (len >= PATH_MAX)
        return bad_path;
    return cleanup_path(pathname);
}

char *perf_path(const char *fmt, ...)
{
    const char *perf_dir = get_perf_dir();
    char *pathname = get_pathname();
    va_list args;
    unsigned len;

    len = strlen(perf_dir);
    if (len > PATH_MAX-100)
        return bad_path;
    memcpy(pathname, perf_dir, len);
    if (len && perf_dir[len-1] != '/')
        pathname[len++] = '/';
    va_start(args, fmt);
    len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
    va_end(args);
    if (len >= PATH_MAX)
        return bad_path;
    return cleanup_path(pathname);
}

/* strip arbitrary amount of directory separators at end of path */
static inline int chomp_trailing_dir_sep(const char *path, int len)
{
    while (len && is_dir_sep(path[len - 1]))
        len--;
    return len;
}

/*
 * If path ends with suffix (complete path components), returns the
 * part before suffix (sans trailing directory separators).
 * Otherwise returns NULL.
 */
char *strip_path_suffix(const char *path, const char *suffix)
{
    int path_len = strlen(path), suffix_len = strlen(suffix);

    while (suffix_len) {
        if (!path_len)
            return NULL;

        if (is_dir_sep(path[path_len - 1])) {
            if (!is_dir_sep(suffix[suffix_len - 1]))
                return NULL;
            path_len = chomp_trailing_dir_sep(path, path_len);
            suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
        }
        else if (path[--path_len] != suffix[--suffix_len])
            return NULL;
    }

    if (path_len && !is_dir_sep(path[path_len - 1]))
        return NULL;
    return strndup(path, chomp_trailing_dir_sep(path, path_len));
}