/*
 * 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 ".";
}

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;
}


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;
}

char *mksnpath(char *buf, size_t n, const char *fmt, ...)
{
        va_list args;
        unsigned len;

        va_start(args, fmt);
        len = vsnprintf(buf, n, fmt, args);
        va_end(args);
        if (len >= n) {
                strlcpy(buf, bad_path, n);
                return buf;
        }
        return cleanup_path(buf);
}

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_snpath(char *buf, size_t n, const char *fmt, ...)
{
        va_list args;
        va_start(args, fmt);
        (void)perf_vsnpath(buf, n, fmt, args);
        va_end(args);
        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);
}


/* perf_mkstemp() - create tmp file honoring TMPDIR variable */
int perf_mkstemp(char *path, size_t len, const char *template)
{
        const char *tmp;
        size_t n;

        tmp = getenv("TMPDIR");
        if (!tmp)
                tmp = "/tmp";
        n = snprintf(path, len, "%s/%s", tmp, template);
        if (len <= n) {
                errno = ENAMETOOLONG;
                return -1;
        }
        return mkstemp(path);
}


const char *make_relative_path(const char *abs_path, const char *base)
{
        static char buf[PATH_MAX + 1];
        int baselen;

        if (!base)
                return abs_path;

        baselen = strlen(base);
        if (prefixcmp(abs_path, base))
                return abs_path;
        if (abs_path[baselen] == '/')
                baselen++;
        else if (base[baselen - 1] != '/')
                return abs_path;

        strcpy(buf, abs_path + baselen);

        return buf;
}

/*
 * It is okay if dst == src, but they should not overlap otherwise.
 *
 * Performs the following normalizations on src, storing the result in dst:
 * - Ensures that components are separated by '/' (Windows only)
 * - Squashes sequences of '/'.
 * - Removes "." components.
 * - Removes ".." components, and the components the precede them.
 * Returns failure (non-zero) if a ".." component appears as first path
 * component anytime during the normalization. Otherwise, returns success (0).
 *
 * Note that this function is purely textual.  It does not follow symlinks,
 * verify the existence of the path, or make any system calls.
 */
int normalize_path_copy(char *dst, const char *src)
{
        char *dst0;

        if (has_dos_drive_prefix(src)) {
                *dst++ = *src++;
                *dst++ = *src++;
        }
        dst0 = dst;

        if (is_dir_sep(*src)) {
                *dst++ = '/';
                while (is_dir_sep(*src))
                        src++;
        }

        for (;;) {
                char c = *src;

                /*
                 * A path component that begins with . could be
                 * special:
                 * (1) "." and ends   -- ignore and terminate.
                 * (2) "./"           -- ignore them, eat slash and continue.
                 * (3) ".." and ends  -- strip one and terminate.
                 * (4) "../"          -- strip one, eat slash and continue.
                 */
                if (c == '.') {
                        if (!src[1]) {
                                /* (1) */
                                src++;
                        } else if (is_dir_sep(src[1])) {
                                /* (2) */
                                src += 2;
                                while (is_dir_sep(*src))
                                        src++;
                                continue;
                        } else if (src[1] == '.') {
                                if (!src[2]) {
                                        /* (3) */
                                        src += 2;
                                        goto up_one;
                                } else if (is_dir_sep(src[2])) {
                                        /* (4) */
                                        src += 3;
                                        while (is_dir_sep(*src))
                                                src++;
                                        goto up_one;
                                }
                        }
                }

                /* copy up to the next '/', and eat all '/' */
                while ((c = *src++) != '\0' && !is_dir_sep(c))
                        *dst++ = c;
                if (is_dir_sep(c)) {
                        *dst++ = '/';
                        while (is_dir_sep(c))
                                c = *src++;
                        src--;
                } else if (!c)
                        break;
                continue;

        up_one:
                /*
                 * dst0..dst is prefix portion, and dst[-1] is '/';
                 * go up one level.
                 */
                dst--;  /* go to trailing '/' */
                if (dst <= dst0)
                        return -1;
                /* Windows: dst[-1] cannot be backslash anymore */
                while (dst0 < dst && dst[-1] != '/')
                        dst--;
        }
        *dst = '\0';
        return 0;
}

/*
 * path = Canonical absolute path
 * prefix_list = Colon-separated list of absolute paths
 *
 * Determines, for each path in prefix_list, whether the "prefix" really
 * is an ancestor directory of path.  Returns the length of the longest
 * ancestor directory, excluding any trailing slashes, or -1 if no prefix
 * is an ancestor.  (Note that this means 0 is returned if prefix_list is
 * "/".) "/foo" is not considered an ancestor of "/foobar".  Directories
 * are not considered to be their own ancestors.  path must be in a
 * canonical form: empty components, or "." or ".." components are not
 * allowed.  prefix_list may be null, which is like "".
 */
int longest_ancestor_length(const char *path, const char *prefix_list)
{
        char buf[PATH_MAX+1];
        const char *ceil, *colon;
        int len, max_len = -1;

        if (prefix_list == NULL || !strcmp(path, "/"))
                return -1;

        for (colon = ceil = prefix_list; *colon; ceil = colon+1) {
                for (colon = ceil; *colon && *colon != PATH_SEP; colon++);
                len = colon - ceil;
                if (len == 0 || len > PATH_MAX || !is_absolute_path(ceil))
                        continue;
                strlcpy(buf, ceil, len+1);
                if (normalize_path_copy(buf, buf) < 0)
                        continue;
                len = strlen(buf);
                if (len > 0 && buf[len-1] == '/')
                        buf[--len] = '\0';

                if (!strncmp(path, buf, len) &&
                    path[len] == '/' &&
                    len > max_len) {
                        max_len = len;
                }
        }

        return max_len;
}

/* 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 xstrndup(path, chomp_trailing_dir_sep(path, path_len));
}