qemu/util/path.c

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/* Code to mangle pathnames into those matching a given prefix.
eg. open("/lib/foo.so") => open("/usr/gnemul/i386-linux/lib/foo.so");
The assumption is that this area does not change.
*/
#include "qemu/osdep.h"
#include <sys/param.h>
#include <dirent.h>
#include "qemu/cutils.h"
#include "qemu/path.h"
#include "qemu/thread.h"
static const char *base;
static GHashTable *hash;
static QemuMutex lock;
void init_paths(const char *prefix)
{
if (prefix[0] == '\0' || !strcmp(prefix, "/")) {
return;
}
if (prefix[0] == '/') {
base = g_strdup(prefix);
} else {
char *cwd = g_get_current_dir();
base = g_build_filename(cwd, prefix, NULL);
g_free(cwd);
}
hash = g_hash_table_new(g_str_hash, g_str_equal);
qemu_mutex_init(&lock);
}
/* Look for path in emulation dir, otherwise return name. */
const char *path(const char *name)
{
gpointer key, value;
const char *ret;
/* Only do absolute paths: quick and dirty, but should mostly be OK. */
if (!base || !name || name[0] != '/') {
return name;
}
qemu_mutex_lock(&lock);
/* Have we looked up this file before? */
if (g_hash_table_lookup_extended(hash, name, &key, &value)) {
ret = value ? value : name;
} else {
char *save = g_strdup(name);
char *full = g_build_filename(base, name, NULL);
/* Look for the path; record the result, pass or fail. */
if (access(full, F_OK) == 0) {
/* Exists. */
g_hash_table_insert(hash, save, full);
ret = full;
} else {
/* Does not exist. */
g_free(full);
g_hash_table_insert(hash, save, NULL);
ret = name;
}
}
qemu_mutex_unlock(&lock);
return ret;
}