path.c

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// SPDX-License-Identifier: GPL-2.0
/*
 * 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"
#include "path.h"
#include <linux/kernel.h>
#include <limits.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <unistd.h>

static char bad_path[] = "/bad-path/";
/*
 * One hack:
 */
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 *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);
}

int path__join(char *bf, size_t size, const char *path1, const char *path2)
{
    return scnprintf(bf, size, "%s%s%s", path1, path1[0] ? "/" : "", path2);
}

int path__join3(char *bf, size_t size, const char *path1, const char *path2, const char *path3)
{
    return scnprintf(bf, size, "%s%s%s%s%s", path1, path1[0] ? "/" : "",
             path2, path2[0] ? "/" : "", path3);
}

bool is_regular_file(const char *file)
{
    struct stat st;

    if (stat(file, &st))
        return false;

    return S_ISREG(st.st_mode);
}

/* Helper function for filesystems that return a dent->d_type DT_UNKNOWN */
bool is_directory(const char *base_path, const struct dirent *dent)
{
    char path[PATH_MAX];
    struct stat st;

    sprintf(path, "%s/%s", base_path, dent->d_name);
    if (stat(path, &st))
        return false;

    return S_ISDIR(st.st_mode);
}