Add external command functionalityHEADmaster

1 files changed, 111 insertions, 4 deletions

diff --git a/status.c b/status.c
index 935b933..43ccfb7 100644
--- a/status.c
+++ b/status.c
@@ -1,5 +1,6 @@
 #include <arpa/inet.h>
 #include <assert.h>
+#include <err.h>
 #include <errno.h>
 #include <ifaddrs.h>
 #include <linux/if.h>
@@ -72,6 +73,7 @@ void get_all_bat_status(char* buf);
 void get_net_link_status(char* buf);
 int element_wifi(char* buf, char* link_name);
 static void update_statusbuffer(char* buf);
+int element_command(char* buf, char* command);
 
 /* Data */
 static char* battery_level_icon[] = {
@@ -94,9 +96,9 @@ static struct element statusbar[] = {
   /*{update_func_t, {minutes, seconds}, {0}, {0}},*/
   [ELEMENT_INVALID] = {NULL, NULL, {0}, {0}, {0}},
 
-#define ELEMENT(name, arg, minutes, seconds)                                   \
-  [ELEMENT_##name] = {                                                         \
-    element_##name,                                                            \
+#define ELEMENT(identifier, function, arg, minutes, seconds)                   \
+  [ELEMENT_##identifier] = {                                                   \
+    element_##function,                                                        \
     arg,                                                                       \
     {(minutes * 60) + ((int)seconds), (long)(seconds * 1000000) % 1000000},    \
     {0},                                                                       \
@@ -366,6 +368,111 @@ element_wifi(char* buf, char* link_name) {
 
 /* external commands */
 /* I just couldn't be bothered to learn pipewire */
+int
+element_command(char* buf, char* command) {
+  int output[2];
+  if (pipe(output) == -1) {
+    err(EXIT_FAILURE, "Failed to create pipe");
+  }
+
+  pid_t pid = fork();
+  if (pid == -1) {
+    err(EXIT_FAILURE, "Failed to fork new process");
+  }
+
+  if (!pid) {
+    close(output[0]);
+
+    // Redirect stdout to output[1]
+    if (dup2(output[1], STDOUT_FILENO) == -1) {
+      err(EXIT_FAILURE, "Failed to redirect stdout");
+    }
+
+    // Redirect stderr to stdout
+    if (dup2(STDOUT_FILENO, STDERR_FILENO) == -1) {
+      err(EXIT_FAILURE, "Failed to redirect stderr");
+    }
+
+    size_t cmd_orig_len = strlen(command);
+
+    if (cmd_orig_len >= 115) {
+      err(EXIT_FAILURE, "Command too long");
+    }
+
+    char cmd[128] = "/usr/bin/env ";     // 13 characters
+    strncat(cmd, command, 128 - 13 - 1); // copies at most 115 bytes
+    size_t cmd_len = strlen(cmd);
+
+    char* args[64];
+    size_t argc  = 0;
+
+    char escaped = '\0'; // Bloody hope there's no more nested args than 4
+
+    // Create args from cmd
+    // First arg is always the first "word"
+    args[argc++] = &cmd[0];
+
+    // Delimeter with zero-bytes at every space, except between single or double
+    // quotes.
+    size_t i;
+    for (i = 0; i < cmd_len; i++) {
+      // Reset the escaped character
+      if (cmd[i] == escaped) {
+        escaped = '\0';
+        cmd[i]  = '\0';
+        continue;
+      }
+
+      // Set escaped character
+      if (!escaped && (cmd[i] == '\'' || cmd[i] == '"')) {
+        escaped = cmd[i];
+        // Remove the escaped character from the argument
+        (args[argc - 1])++;
+        continue;
+      }
+
+      // Don't insert zero-chars until we're un-escaped again
+      if (escaped) {
+        continue;
+      }
+
+      if (cmd[i] == ' ') {
+        cmd[i]       = '\0';
+        args[argc++] = &cmd[i + 1];
+      }
+    }
+
+    if (i == 0) {
+      err(EXIT_FAILURE, "Empty command");
+    }
+
+    // NULL terminated array
+    args[argc] = NULL;
+
+    if (execvp(args[0], args) == -1) {
+      err(EXIT_FAILURE, "Failed to exec");
+    }
+    exit(EXIT_FAILURE);
+  }
+
+  close(output[1]);
+  size_t n = 0;
+  size_t m = 0;
+
+  while (m < ELEMENT_STRBUF_SZ &&
+         (n = read(output[0], &buf[m], ELEMENT_STRBUF_SZ - 1 - m)) > 0) {
+    m += n;
+  }
+
+  buf[m] = '\0';
+
+  for (size_t i = 0; buf[i] != '\0'; i++) {
+    if (buf[i] == '\n')
+      buf[i] = ' ';
+  }
+
+  return 0;
+}
 
 static struct timespec
 time_add(struct timespec a, struct timespec b) {
@@ -448,7 +555,7 @@ update_element_thread(union sigval sv) {
   // Empty queue
   while (mq_receive(mq_data.mqfd, (char*)&msg, sizeof(struct message_t),
                     NULL) != -1) {
-    fprintf(stderr, "%d on %d\n", msg.action, msg.element);
+    //fprintf(stderr, "%d on %d\n", msg.action, msg.element);
     if (msg.action != update || msg.element <= ELEMENT_INVALID ||
         msg.element > ELEMENT_MAX) {
       fprintf(stderr, "Invalid action/element\n");