syscalls: fix execve to use heap and make it work better with fork

src/tasking/syscalls.c

@@ -331,68 +331,68 @@ extern void execve_return(TrapFrame *tf);
 /**
  * this might be a not really good implementation as it only supports
  * up to EXECVE_MAX_ARGUMENT_SIZE characters in each argument or environment
- * string and for some reason I was unable to use malloc for kernel_argv and
+ * string
- * kernel_envp
 */
 int sys_execve(TrapFrame *tf) {
     const char* filename = (const char*)tf->ebx;
-
     char **argv = (char**)tf->ecx;
     char **envp = (char**)tf->edx;
 
     int argc = 0;
+    while(argv[argc] != NULL) argc++;
+
     int envc = 0;
+    while(envp[envc] != NULL) envc++;
 
-    while(argv[argc] != NULL)
+    char** kernel_argv = malloc((argc + 1) * sizeof(char*));
-    {
+    if (!kernel_argv) return -1;
-        argc++;
-    }
-    while(envp[envc] != NULL)
-    {
-        envc++;
-    }
 
-    //TODO: check why was there a triple fault when I tried using malloc
+    for(int i = 0; i < argc; i++) {
-    char kernel_argv[argc][EXECVE_MAX_ARGUMENT_SIZE];
+        kernel_argv[i] = malloc(EXECVE_MAX_ARGUMENT_SIZE);
-    char kernel_envp[envc][EXECVE_MAX_ARGUMENT_SIZE];
-
-    for(int i = 0; i < argc; i++)
-    {
         strcpy(kernel_argv[i], argv[i]);
     }
+    kernel_argv[argc] = NULL;
 
-    for(int i = 0; i < envc; i++)
+    char** kernel_envp = malloc((envc + 1) * sizeof(char*));
-    {
+    if (!kernel_envp) return -1; // TODO: cleanup kernel_argv
+
+    for(int i = 0; i < envc; i++) {
+        kernel_envp[i] = malloc(EXECVE_MAX_ARGUMENT_SIZE);
         strcpy(kernel_envp[i], envp[i]);
     }
+    kernel_envp[envc] = NULL;
 
     uint8_t* file_buffer;
     int err = vfs_read_file_by_path(filename, &file_buffer);
     if (err != 0) {
-        debug_log("execve: failed to read file '%s'\n", filename);
+        // TODO: Free kernel_argv/envp
+        debug_log("execve: failed to read file\n");
         return -1;
     }
 
     Elf32_Ehdr *elf_header = (Elf32_Ehdr*)file_buffer;
     if (memcmp(elf_header->e_ident, "\x7F" "ELF", 4) != 0) {
-        debug_log("execve: '%s' is not a valid ELF file\n", filename);
+        // TODO: Free resources
-        free(file_buffer);
         return -1;
     }
 
     uint32_t* new_page_dir = create_page_dir();
-    if (!new_page_dir) {
+    if (!new_page_dir) return -1;
-        free(file_buffer);
-        return -1;
-    }
-    uint32_t new_page_dir_phys = (uint32_t)get_physaddr((void*)new_page_dir);
-    uint32_t* old_page_dir_to_free = current->pagedir;
 
-    set_page_dir(new_page_dir_phys);
+    uint32_t new_page_dir_phys = (uint32_t)get_physaddr((void*)new_page_dir);
-    current->pagedir = new_page_dir;
+
+    void* process_phys = get_physaddr(current);
+    map_page_in_directory(new_page_dir, process_phys, current, PAGE_PRESENT | PAGE_RW);
 
     void* kstack_phys = get_physaddr(current->kstack);
-    map_page(kstack_phys, current->kstack, PAGE_PRESENT | PAGE_RW);
+    map_page_in_directory(new_page_dir, kstack_phys, current->kstack, PAGE_PRESENT | PAGE_RW);
+
+    void* argv_phys = get_physaddr(kernel_argv);
+    map_page_in_directory(new_page_dir, argv_phys, kernel_argv, PAGE_PRESENT | PAGE_RW);
+
+    uint32_t* old_page_dir_to_free = current->pagedir;
+    set_page_dir(new_page_dir_phys);
+    current->pagedir = new_page_dir;
 
     uint32_t highest_vaddr = 0;
     for (int i = 0; i < elf_header->e_phnum; i++) {
@@ -400,7 +400,6 @@ int sys_execve(TrapFrame *tf) {
         if (p_header->p_type == PT_LOAD) {
             uint32_t start_addr = p_header->p_vaddr;
             uint32_t end_addr = start_addr + p_header->p_memsz;
-
             uint32_t start_page = start_addr & ~0xFFF;
             uint32_t end_page = (end_addr - 1) & ~0xFFF;
 
@@ -413,9 +412,7 @@ int sys_execve(TrapFrame *tf) {
             if (p_header->p_memsz > p_header->p_filesz) {
                 memset((void*)(p_header->p_vaddr + p_header->p_filesz), 0, p_header->p_memsz - p_header->p_filesz);
             }
-            if (p_header->p_vaddr + p_header->p_memsz > highest_vaddr) {
+            if (end_addr > highest_vaddr) highest_vaddr = end_addr;
-                highest_vaddr = p_header->p_vaddr + p_header->p_memsz;
-            }
         }
     }
 
@@ -426,7 +423,6 @@ int sys_execve(TrapFrame *tf) {
 
     uint32_t user_esp = USER_STACK_TOP;
     
-    //push environment strings
     uint32_t envp_pointers[envc + 1];
     for (int i = envc - 1; i >= 0; i--) {
         size_t len = strlen(kernel_envp[i]) + 1;
@@ -434,9 +430,8 @@ int sys_execve(TrapFrame *tf) {
         memcpy((void*)user_esp, kernel_envp[i], len);
         envp_pointers[i] = user_esp;
     }
-    envp_pointers[envc] = 0;//null terminator
+    envp_pointers[envc] = 0;
-    
+
-    //push argument strings
     uint32_t argv_pointers[argc + 1];
     for (int i = argc - 1; i >= 0; i--) {
         size_t len = strlen(kernel_argv[i]) + 1;
@@ -444,22 +439,25 @@ int sys_execve(TrapFrame *tf) {
         memcpy((void*)user_esp, kernel_argv[i], len);
         argv_pointers[i] = user_esp;
     }
-    argv_pointers[argc] = 0;//null terminator
+    argv_pointers[argc] = 0;
 
-    //push envp pointers
     user_esp -= (envc + 1) * sizeof(uint32_t);
     memcpy((void*)user_esp, envp_pointers, (envc + 1) * sizeof(uint32_t));
     
-    //push argv pointers
     user_esp -= (argc + 1) * sizeof(uint32_t);
     memcpy((void*)user_esp, argv_pointers, (argc + 1) * sizeof(uint32_t));
     
-    //push argc
     user_esp -= sizeof(uint32_t);
     *((uint32_t*)user_esp) = argc;
 
     current->brk = (void*)(DivRoundUp(highest_vaddr, PAGE_SIZE) * PAGE_SIZE);
+    
     free(file_buffer);
+    for(int i=0; i<argc; i++) free(kernel_argv[i]);
+    free(kernel_argv);
+    for(int i=0; i<envc; i++) free(kernel_envp[i]);
+    free(kernel_envp);
+
     destroy_page_dir(old_page_dir_to_free);
 
     tf->gs = SEG_UDATA | DPL_USER;
@@ -475,7 +473,6 @@ int sys_execve(TrapFrame *tf) {
     tf->usermode_ss = SEG_UDATA | DPL_USER;
 
     execve_return(tf);
-
     return 0;
 }