util: Split out exec_dir from os_find_datadir

With this change, main() calls qemu_init_exec_dir and uses argv[0] to
init exec_dir. The saved value can be retrieved with
qemu_get_exec_dir later. It will be reused by module loading.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/qemu-common.h

@@ -360,7 +360,7 @@ char *qemu_find_file(int type, const char *name);
 
 /* OS specific functions */
 void os_setup_early_signal_handling(void);
-char *os_find_datadir(const char *argv0);
+char *os_find_datadir(void);
 void os_parse_cmd_args(int index, const char *optarg);
 void os_pidfile_error(void);
 

include/qemu/osdep.h

@@ -215,6 +215,15 @@ bool fips_get_state(void);
  */
 char *qemu_get_local_state_pathname(const char *relative_pathname);
 
+/* Find program directory, and save it for later usage with
+ * qemu_get_exec_dir().
+ * Try OS specific API first, if not working, parse from argv0. */
+void qemu_init_exec_dir(const char *argv0);
+
+/* Get the saved exec dir.
+ * Caller needs to release the returned string by g_free() */
+char *qemu_get_exec_dir(void);
+
 /**
  * qemu_getauxval:
  * @type: the auxiliary vector key to lookup

os-posix.c

@@ -84,46 +84,17 @@ void os_setup_signal_handling(void)
    running from the build tree this will be "$bindir/../pc-bios".  */
 #define SHARE_SUFFIX "/share/qemu"
 #define BUILD_SUFFIX "/pc-bios"
-char *os_find_datadir(const char *argv0)
+char *os_find_datadir(void)
 {
-    char *dir;
-    char *p = NULL;
+    char *dir, *exec_dir;
     char *res;
-    char buf[PATH_MAX];
     size_t max_len;
 
-#if defined(__linux__)
-    {
-        int len;
-        len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
-        if (len > 0) {
-            buf[len] = 0;
-            p = buf;
-        }
-    }
-#elif defined(__FreeBSD__)
-    {
-        static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
-        size_t len = sizeof(buf) - 1;
-
-        *buf = '\0';
-        if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
-            *buf) {
-            buf[sizeof(buf) - 1] = '\0';
-            p = buf;
-        }
-    }
-#endif
-    /* If we don't have any way of figuring out the actual executable
-       location then try argv[0].  */
-    if (!p) {
-        p = realpath(argv0, buf);
-        if (!p) {
+    exec_dir = qemu_get_exec_dir();
+    if (exec_dir == NULL) {
         return NULL;
     }
-    }
-    dir = dirname(p);
-    dir = dirname(dir);
+    dir = dirname(exec_dir);
 
     max_len = strlen(dir) +
         MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1;
@@ -137,6 +108,7 @@ char *os_find_datadir(const char *argv0)
         }
     }
 
+    g_free(exec_dir);
     return res;
 }
 #undef SHARE_SUFFIX

os-win32.c

@@ -84,26 +84,9 @@ void os_setup_early_signal_handling(void)
 }
 
 /* Look for support files in the same directory as the executable.  */
-char *os_find_datadir(const char *argv0)
+char *os_find_datadir(void)
 {
-    char *p;
-    char buf[MAX_PATH];
-    DWORD len;
-
-    len = GetModuleFileName(NULL, buf, sizeof(buf) - 1);
-    if (len == 0) {
-        return NULL;
-    }
-
-    buf[len] = 0;
-    p = buf + len - 1;
-    while (p != buf && *p != '\\')
-        p--;
-    *p = 0;
-    if (access(buf, R_OK) == 0) {
-        return g_strdup(buf);
-    }
-    return NULL;
+    return qemu_get_exec_dir();
 }
 
 void os_set_line_buffering(void)

qemu-img.c

@@ -2719,6 +2719,7 @@ int main(int argc, char **argv)
 #endif
 
     error_set_progname(argv[0]);
+    qemu_init_exec_dir(argv[0]);
 
     qemu_init_main_loop();
     bdrv_init();

qemu-io.c

@@ -381,6 +381,7 @@ int main(int argc, char **argv)
 #endif
 
     progname = basename(argv[0]);
+    qemu_init_exec_dir(argv[0]);
 
     while ((c = getopt_long(argc, argv, sopt, lopt, &opt_index)) != -1) {
         switch (c) {

qemu-nbd.c

@@ -376,6 +376,7 @@ int main(int argc, char **argv)
     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
     sa_sigterm.sa_handler = termsig_handler;
     sigaction(SIGTERM, &sa_sigterm, NULL);
+    qemu_init_exec_dir(argv[0]);
 
     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
         switch (ch) {

util/oslib-posix.c

@@ -57,6 +57,7 @@ extern int daemon(int, int);
 #include "trace.h"
 #include "qemu/sockets.h"
 #include <sys/mman.h>
+#include <libgen.h>
 
 #ifdef CONFIG_LINUX
 #include <sys/syscall.h>
@@ -274,3 +275,56 @@ void qemu_set_tty_echo(int fd, bool echo)
 
     tcsetattr(fd, TCSANOW, &tty);
 }
+
+static char exec_dir[PATH_MAX];
+
+void qemu_init_exec_dir(const char *argv0)
+{
+    char *dir;
+    char *p = NULL;
+    char buf[PATH_MAX];
+
+    assert(!exec_dir[0]);
+
+#if defined(__linux__)
+    {
+        int len;
+        len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
+        if (len > 0) {
+            buf[len] = 0;
+            p = buf;
+        }
+    }
+#elif defined(__FreeBSD__)
+    {
+        static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
+        size_t len = sizeof(buf) - 1;
+
+        *buf = '\0';
+        if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
+            *buf) {
+            buf[sizeof(buf) - 1] = '\0';
+            p = buf;
+        }
+    }
+#endif
+    /* If we don't have any way of figuring out the actual executable
+       location then try argv[0].  */
+    if (!p) {
+        if (!argv0) {
+            return;
+        }
+        p = realpath(argv0, buf);
+        if (!p) {
+            return;
+        }
+    }
+    dir = dirname(p);
+
+    pstrcpy(exec_dir, sizeof(exec_dir), dir);
+}
+
+char *qemu_get_exec_dir(void)
+{
+    return g_strdup(exec_dir);
+}

util/oslib-win32.c

@@ -208,3 +208,33 @@ void qemu_set_tty_echo(int fd, bool echo)
                        dwMode & ~(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT));
     }
 }
+
+static char exec_dir[PATH_MAX];
+
+void qemu_init_exec_dir(const char *argv0)
+{
+
+    char *p;
+    char buf[MAX_PATH];
+    DWORD len;
+
+    len = GetModuleFileName(NULL, buf, sizeof(buf) - 1);
+    if (len == 0) {
+        return;
+    }
+
+    buf[len] = 0;
+    p = buf + len - 1;
+    while (p != buf && *p != '\\') {
+        p--;
+    }
+    *p = 0;
+    if (access(buf, R_OK) == 0) {
+        pstrcpy(exec_dir, sizeof(exec_dir), buf);
+    }
+}
+
+char *qemu_get_exec_dir(void)
+{
+    return g_strdup(exec_dir);
+}

vl.c

@@ -2827,6 +2827,7 @@ int main(int argc, char **argv, char **envp)
 
     atexit(qemu_run_exit_notifiers);
     error_set_progname(argv[0]);
+    qemu_init_exec_dir(argv[0]);
 
     g_mem_set_vtable(&mem_trace);
     if (!g_thread_supported()) {
@@ -3855,7 +3856,7 @@ int main(int argc, char **argv, char **envp)
     /* If no data_dir is specified then try to find it relative to the
        executable path.  */
     if (data_dir_idx < ARRAY_SIZE(data_dir)) {
-        data_dir[data_dir_idx] = os_find_datadir(argv[0]);
+        data_dir[data_dir_idx] = os_find_datadir();
         if (data_dir[data_dir_idx] != NULL) {
             data_dir_idx++;
         }