LXR qemu/util/path.c

   1/* Code to mangle pathnames into those matching a given prefix.
   2   eg. open("/lib/foo.so") => open("/usr/gnemul/i386-linux/lib/foo.so");
   3
   4   The assumption is that this area does not change.
   5*/
   6#include "qemu/osdep.h"
   7#include <sys/param.h>
   8#include <dirent.h>
   9#include "qemu/cutils.h"
  10#include "qemu/path.h"
  11#include "qemu/thread.h"
  12
  13static const char *base;
  14static GHashTable *hash;
  15static QemuMutex lock;
  16
  17void init_paths(const char *prefix)
  18{
  19    if (prefix[0] == '\0' || !strcmp(prefix, "/")) {
  20        return;
  21    }
  22
  23    if (prefix[0] == '/') {
  24        base = g_strdup(prefix);
  25    } else {
  26        char *cwd = g_get_current_dir();
  27        base = g_build_filename(cwd, prefix, NULL);
  28        g_free(cwd);
  29    }
  30
  31    hash = g_hash_table_new(g_str_hash, g_str_equal);
  32    qemu_mutex_init(&lock);
  33}
  34
  35/* Look for path in emulation dir, otherwise return name. */
  36const char *path(const char *name)
  37{
  38    gpointer key, value;
  39    const char *ret;
  40
  41    /* Only do absolute paths: quick and dirty, but should mostly be OK.  */
  42    if (!base || !name || name[0] != '/') {
  43        return name;
  44    }
  45
  46    qemu_mutex_lock(&lock);
  47
  48    /* Have we looked up this file before?  */
  49    if (g_hash_table_lookup_extended(hash, name, &key, &value)) {
  50        ret = value ? value : name;
  51    } else {
  52        char *save = g_strdup(name);
  53        char *full = g_build_filename(base, name, NULL);
  54
  55        /* Look for the path; record the result, pass or fail.  */
  56        if (access(full, F_OK) == 0) {
  57            /* Exists.  */
  58            g_hash_table_insert(hash, save, full);
  59            ret = full;
  60        } else {
  61            /* Does not exist.  */
  62            g_free(full);
  63            g_hash_table_insert(hash, save, NULL);
  64            ret = name;
  65        }
  66    }
  67
  68    qemu_mutex_unlock(&lock);
  69    return ret;
  70}
  71