From e28b0347a1977975e5a921e8c3d56239cd48cd40 Mon Sep 17 00:00:00 2001
From: forever2k38 <forever2k38@forever2k38.net>
Date: Sat, 10 Oct 2026 20:40:48 +0200
Subject: permission bits while installing

---
 src/pow_lua.c | 142 +++++++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 107 insertions(+), 35 deletions(-)

(limited to 'src/pow_lua.c')

diff --git a/src/pow_lua.c b/src/pow_lua.c
index 0cd1019..122c62a 100644
--- a/src/pow_lua.c
+++ b/src/pow_lua.c
@@ -30,7 +30,30 @@
 #include "stdlib.h"
 #include "unistd.h"
 #include "string.h"
-#include "sys/sendfile.h"
+#include "fcntl.h"
+#include "sys/stat.h"
+#include "errno.h"
+
+int parse_octal_string(const char *str) {
+    if (str[0] == '0' && (str[1] == 'o' || str[1] == 'O')) {
+        str += 2;
+    } else if (str[0] == '0') {
+        str += 1;
+    }
+    
+    int result = 0;
+    while (*str) {
+        int digit = *str - '0';
+        if (digit < 0 || digit > 7) {
+            errno = EINVAL;
+            return -1;
+        }
+        result = result * 8 + digit;
+        str++;
+    }
+
+    return result;
+}
 
 int pow_lua_extract(lua_State *L) {
   int r;
@@ -145,7 +168,6 @@ int pow_lua_extract(lua_State *L) {
   return 1;
 }
 
-
 int pow_lua_install(lua_State *L) {
   if (!lua_isstring(L, 1)) {
     lua_pushnil(L);
@@ -161,70 +183,120 @@ int pow_lua_install(lua_State *L) {
     return 2;
   }
 
-  char *src = strdup(lua_tostring(L, 1));
+  if (!lua_isstring(L, 3)) {
+    pow_log_info("no permission bit specified for install function, defaulting to 644");
+  }
 
-  if (!src) {
-    pow_log_error("failed to strdup source string");
+  const char *src_str = lua_tostring(L, 1);
+  const char *dest_str = lua_tostring(L, 2);
 
-    return 2;
+  mode_t permission_bit = S_IRUSR | S_IWUSR | S_IROTH | S_IRGRP;
+
+  if (lua_isstring(L, 3)) {
+    char *endptr;
+    unsigned long perms = strtoul(lua_tostring(L, 3), &endptr, 8);
+    if (*endptr != '\0') {
+      lua_pushnil(L);
+      lua_pushstring(L, "invalid octal permission string");
+
+      return 2;
+    }
+    permission_bit = (mode_t)perms;
   }
 
-  char *dest = strdup(lua_tostring(L, 2));
+  pow_log_info("installing: %s to %s", src_str, dest_str);
 
-  if (!dest) {
-    free(src);
+  int src_fd = open(src_str, O_RDONLY);
 
-    pow_log_error("failed to strdup dest string");
+  if (src_fd == -1) {
+    pow_log_error("failed to open source file %s while installing", src_str);
 
     return 2;
   }
 
-  pow_log_info("installing: %s to %s", src, dest);
+  struct stat src_stat = {0};
+  if (fstat(src_fd, &src_stat) == -1) {
+    close(src_fd);
 
-  FILE *src_stream = fopen(src, "r");
+    pow_log_error("failed to stat source file %s while installing", src_str);
 
-  if (!src_stream) {
-    free(src);
-    free(dest);
+    return 2;
+  }
 
-    pow_log_error("failed to open source file %s while installing", src);
+  int dest_fd = open(dest_str, O_WRONLY | O_CREAT | O_TRUNC, permission_bit);
+
+  if (dest_fd == -1) {
+    close(src_fd);
+
+    pow_log_error("failed to open destination file %s for writing while installing", dest_str);
 
     return 2;
   }
 
-  FILE *dest_stream = fopen(dest, "w");
+  char buf[8192];
+  off_t copied = 0;
+  ssize_t bytes_read;
+  ssize_t bytes_written;
+  off_t remaining = src_stat.st_size;
+
+  while (remaining > 0) {
+    size_t to_read = remaining > sizeof(buf) ? sizeof(buf) : remaining;
 
-  if (!dest_stream) {
-    free(src);
-    free(dest);
+    bytes_read = read(src_fd, buf, to_read);
 
-    fclose(src_stream);
+    if (bytes_read == -1) {
+      if (errno == EINTR) {
+        continue;
+      }
 
-    pow_log_error("failed to open destination file %s for writing while installing", dest);
+      pow_log_error("err?");
 
-    return 2;
-  }
+      close(dest_fd);
+      close(src_fd);
 
-  int src_fd = fileno(src_stream);
-  int dest_fd = fileno(dest_stream);
+      return 2;
+    }
 
-  struct stat src_stat = {0};
-  int result = fstat(src_fd, &src_stat);
+    if (bytes_read == 0) {
+      pow_log_error("unexpected EOF during copy");
 
-  off_t copied = 0;
-  while (result == 0 && copied < src_stat.st_size) {
-    ssize_t written = sendfile(dest_fd, src_fd, &copied, SIZE_MAX);
-    copied += written;
+      close(dest_fd);
+      close(src_fd);
 
-    if (written == -1) {
-      result = -1;
+      return 2;
     }
+
+    ssize_t written = 0;
+    while (written < bytes_read) {
+      bytes_written = write(dest_fd, buf + written, bytes_read - written);
+
+      if (bytes_written == -1) {
+        if (errno == EINTR) {
+          continue;
+        }
+
+        pow_log_error("write failed during install");
+
+        close(dest_fd);
+        close(src_fd);
+
+        return 2;
+      }
+
+      written += bytes_written;
+    }
+
+    copied += bytes_read;
+    remaining -= bytes_read;
   }
 
-  if (fchmod(dest_fd, src_stat.st_mode) == -1) {
+  if (fchmod(dest_fd, permission_bit) == -1) {
     pow_log_error("failed to set permission bits, expect breakage!");
   }
 
+  close(dest_fd);
+  close(src_fd);
+
   return 1;
 }
 
-- 
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