Expose sc_get_env() to read environment variable

Contrary to getenv(), sc_get_env() returns an allocated string that is
guaranteed to be encoded in UTF-8 on all platforms (it uses _wgetenv()
internally on Windows and converts the strings).

PR #5560 <https://github.com/Genymobile/scrcpy/pull/5560>

app/meson.build

@@ -46,6 +46,7 @@ src = [
     'src/util/acksync.c',
     'src/util/audiobuf.c',
     'src/util/average.c',
+    'src/util/env.c',
     'src/util/file.c',
     'src/util/intmap.c',
     'src/util/intr.c',

app/src/icon.c

@@ -9,6 +9,7 @@
 
 #include "config.h"
 #include "compat.h"
+#include "util/env.h"
 #include "util/file.h"
 #include "util/log.h"
 #include "util/str.h"
@@ -19,35 +20,22 @@
 
 static char *
 get_icon_path(void) {
-#ifdef __WINDOWS__
-    const wchar_t *icon_path_env = _wgetenv(L"SCRCPY_ICON_PATH");
-#else
-    const char *icon_path_env = getenv("SCRCPY_ICON_PATH");
-#endif
-    if (icon_path_env) {
+    char *icon_path = sc_get_env("SCRCPY_ICON_PATH");
+    if (icon_path) {
         // if the envvar is set, use it
-#ifdef __WINDOWS__
-        char *icon_path = sc_str_from_wchars(icon_path_env);
-#else
-        char *icon_path = strdup(icon_path_env);
-#endif
-        if (!icon_path) {
-            LOG_OOM();
-            return NULL;
-        }
         LOGD("Using SCRCPY_ICON_PATH: %s", icon_path);
         return icon_path;
     }
 
 #ifndef PORTABLE
     LOGD("Using icon: " SCRCPY_DEFAULT_ICON_PATH);
-    char *icon_path = strdup(SCRCPY_DEFAULT_ICON_PATH);
+    icon_path = strdup(SCRCPY_DEFAULT_ICON_PATH);
     if (!icon_path) {
         LOG_OOM();
         return NULL;
     }
 #else
-    char *icon_path = sc_file_get_local_path(SCRCPY_PORTABLE_ICON_FILENAME);
+    icon_path = sc_file_get_local_path(SCRCPY_PORTABLE_ICON_FILENAME);
     if (!icon_path) {
         LOGE("Could not get icon path");
         return NULL;

app/src/server.c

@@ -9,6 +9,7 @@
 
 #include "adb/adb.h"
 #include "util/binary.h"
+#include "util/env.h"
 #include "util/file.h"
 #include "util/log.h"
 #include "util/net_intr.h"
@@ -25,35 +26,22 @@
 
 static char *
 get_server_path(void) {
-#ifdef __WINDOWS__
-    const wchar_t *server_path_env = _wgetenv(L"SCRCPY_SERVER_PATH");
-#else
-    const char *server_path_env = getenv("SCRCPY_SERVER_PATH");
-#endif
-    if (server_path_env) {
+    char *server_path = sc_get_env("SCRCPY_SERVER_PATH");
+    if (server_path) {
         // if the envvar is set, use it
-#ifdef __WINDOWS__
-        char *server_path = sc_str_from_wchars(server_path_env);
-#else
-        char *server_path = strdup(server_path_env);
-#endif
-        if (!server_path) {
-            LOG_OOM();
-            return NULL;
-        }
         LOGD("Using SCRCPY_SERVER_PATH: %s", server_path);
         return server_path;
     }
 
 #ifndef PORTABLE
     LOGD("Using server: " SC_SERVER_PATH_DEFAULT);
-    char *server_path = strdup(SC_SERVER_PATH_DEFAULT);
+    server_path = strdup(SC_SERVER_PATH_DEFAULT);
     if (!server_path) {
         LOG_OOM();
         return NULL;
     }
 #else
-    char *server_path = sc_file_get_local_path(SC_SERVER_FILENAME);
+    server_path = sc_file_get_local_path(SC_SERVER_FILENAME);
     if (!server_path) {
         LOGE("Could not get local file path, "
              "using " SC_SERVER_FILENAME " from current directory");

app/src/util/env.c

@@ -0,0 +1,29 @@
+#include "env.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include "util/str.h"
+
+char *
+sc_get_env(const char *varname) {
+#ifdef _WIN32
+    wchar_t *w_varname = sc_str_to_wchars(varname);
+    if (!w_varname) {
+         return NULL;
+    }
+    const wchar_t *value = _wgetenv(w_varname);
+    free(w_varname);
+    if (!value) {
+        return NULL;
+    }
+
+    return sc_str_from_wchars(value);
+#else
+    const char *value = getenv(varname);
+    if (!value) {
+        return NULL;
+    }
+
+    return strdup(value);
+#endif
+}

app/src/util/env.h

@@ -0,0 +1,12 @@
+#ifndef SC_ENV_H
+#define SC_ENV_H
+
+#include "common.h"
+
+// Return the value of the environment variable (may be NULL).
+//
+// The returned value must be freed by the caller.
+char *
+sc_get_env(const char *varname);
+
+#endif