feat(buffer): ability to read from stdin

.vscode/launch.json

@@ -51,6 +51,30 @@
           "ignoreFailures": true
         }
       ]
+    },
+    {
+      "name": "swappy - stdin",
+      "type": "cppdbg",
+      "request": "launch",
+      "program": "${workspaceFolder}/build/meson-out/swappy",
+      "args": ["-f", "-"],
+      "stopAtEntry": false,
+      "cwd": "${workspaceFolder}",
+      "environment": [
+        {
+          "name": "G_MESSAGES_DEBUG",
+          "value": "all"
+        }
+      ],
+      "externalConsole": false,
+      "MIMode": "gdb",
+      "setupCommands": [
+        {
+          "description": "Enable pretty-printing for gdb",
+          "text": "-enable-pretty-printing",
+          "ignoreFailures": true
+        }
+      ]
     }
   ]
 }

include/file.h

@@ -2,3 +2,4 @@
 
 bool folder_exists(const char *path);
 bool file_exists(const char *path);
+char *file_dump_stdin_into_a_temp_file();

src/application.c

@@ -157,6 +157,7 @@ void application_finish(struct swappy_state *state) {
   cairo_surface_destroy(state->cairo_surface);
   cairo_surface_destroy(state->image_surface);
   g_free(state->storage_path);
+  g_free(state->file_str);
   g_free(state->geometry_str);
   g_free(state->geometry);
   g_free(state->ui);
@@ -531,19 +532,8 @@ static gboolean has_option_file(struct swappy_state *state) {
   return (state->file_str != NULL);
 }
 
-static gboolean is_file_valid(const char *file) {
-  cairo_surface_t *surface = cairo_image_surface_create_from_png(file);
-  cairo_status_t status = cairo_surface_status(surface);
-
-  if (status) {
-    g_warning("error while loading: %s - cairo status: %s", file,
-              cairo_status_to_string(status));
-    return false;
-  }
-
-  cairo_surface_destroy(surface);
-
-  return true;
+static gboolean is_file_from_stdin(const char *file) {
+  return (strcmp(file, "-") == 0);
 }
 
 static gint command_line_handler(GtkApplication *app,
@@ -560,8 +550,10 @@ static gint command_line_handler(GtkApplication *app,
   }
 
   if (has_option_file(state)) {
-    if (!is_file_valid(state->file_str)) {
-      return EXIT_FAILURE;
+    if (is_file_from_stdin(state->file_str)) {
+      char *new_file_str = file_dump_stdin_into_a_temp_file();
+      g_free(state->file_str);
+      state->file_str = new_file_str;
     }
 
     if (!buffer_init_from_file(state)) {

src/buffer.c

@@ -178,8 +178,13 @@ bool buffer_init_from_file(struct swappy_state *state) {
   char *file = state->file_str;
 
   cairo_surface_t *surface = cairo_image_surface_create_from_png(file);
+  cairo_status_t status = cairo_surface_status(surface);
 
-  g_assert(surface);
+  if (status) {
+    g_warning("error while loading png file: %s - cairo status: %s", file,
+              cairo_status_to_string(status));
+    return false;
+  }
 
   int width = cairo_image_surface_get_width(surface);
   int height = cairo_image_surface_get_height(surface);

src/file.c

@@ -1,7 +1,15 @@
 #define _POSIX_C_SOURCE 200112L
 
+#include <errno.h>
+#include <fcntl.h>
+#include <glib.h>
+#include <glib/gstdio.h>
 #include <stdbool.h>
 #include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#define BLOCK_SIZE 1024
 
 bool folder_exists(const char *path) {
   struct stat sb;
@@ -18,3 +26,44 @@ bool file_exists(const char *path) {
 
   return (stat(path, &sb) == 0 && S_ISREG(sb.st_mode));
 }
+
+char *file_dump_stdin_into_a_temp_file() {
+  char buf[BLOCK_SIZE];
+  GError *error = NULL;
+
+  if (isatty(STDIN_FILENO)) {
+    g_warning("stdin is a tty");
+    return NULL;
+  }
+
+  // Reopen stdin as binary mode
+  g_freopen(NULL, "rb", stdin);
+
+  const gchar *tempdir = g_get_tmp_dir();
+  gchar filename[] = "swappy-stdin-XXXXXX.png";
+  gchar *ret = g_build_filename(tempdir, filename, NULL);
+  gint fd = g_mkstemp(ret);
+
+  if (fd == -1) {
+    g_warning("unable to dump stdin into temporary file");
+    return NULL;
+  }
+
+  g_info("writing stdin content into filepath: %s", ret);
+
+  size_t count = 1;
+  while (count > 0) {
+    count = fread(buf, 1, sizeof(buf), stdin);
+    write(fd, &buf, count);
+  }
+
+  g_close(fd, &error);
+
+  if (error) {
+    g_warning("unable to close temporary file: %s", error->message);
+    g_error_free(error);
+    return NULL;
+  }
+
+  return ret;
+}