[elf] Separate exec and system

kernel/core/elf.c

@@ -35,69 +35,79 @@ exec(
 		int     argc, /* Argument count (ie, /bin/echo hello world = 3) */
 		char ** argv  /* Argument strings (including executable path) */
 	) {
-	/* This is technically system(), so we're forking */
+	/* Open the file */
-	int child = fork();
+	fs_node_t * file = kopen(path,0);
-	if (child == 0) {
+	if (!file) {
-		/* Open the file */
+		/* Command not found */
-		fs_node_t * file = kopen(path,0);
+		kexit(127);
-		if (!file) {
+	}
-			/* Command not found */
+	/* Read in the binary contents */
-			kexit(127);
+	Elf32_Header * header = (Elf32_Header *)malloc(file->length + 100);
-		}
+	read_fs(file, 0, file->length, (uint8_t *)header);
-		/* Read in the binary contents */
-		Elf32_Header * header = (Elf32_Header *)malloc(file->length + 100);
-		read_fs(file, 0, file->length, (uint8_t *)header);
 
-		/* Alright, we've read the binary, time to load the loadable sections */
+	/* Alright, we've read the binary, time to load the loadable sections */
-		/* Verify the magic */
+	/* Verify the magic */
-		if (	header->e_ident[0] != ELFMAG0 ||
+	if (	header->e_ident[0] != ELFMAG0 ||
-				header->e_ident[1] != ELFMAG1 ||
+			header->e_ident[1] != ELFMAG1 ||
-				header->e_ident[2] != ELFMAG2 ||
+			header->e_ident[2] != ELFMAG2 ||
-				header->e_ident[3] != ELFMAG3) {
+			header->e_ident[3] != ELFMAG3) {
-			/* What? This isn't an ELF... */
+		/* What? This isn't an ELF... */
-			kprintf("Fatal: Not a valid ELF executable.\n");
+		kprintf("Fatal: Not a valid ELF executable.\n");
-			free(header);
-			close_fs(file);
-			kexit(127);
-		}
-
-		/* Load the loadable segments from the binary */
-		for (uintptr_t x = 0; x < header->e_shentsize * header->e_shnum; x += header->e_shentsize) {
-			/* read a section header */
-			Elf32_Shdr * shdr = (Elf32_Shdr *)((uintptr_t)header + (header->e_shoff + x));
-			if (shdr->sh_addr) {
-				/* If this is a loadable section, load it up. */
-				if (shdr->sh_addr < current_task->entry) {
-					/* If this is the lowest entry point, store it for memory reasons */
-					current_task->entry = shdr->sh_addr;
-				}
-				if (shdr->sh_addr + shdr->sh_size - current_task->entry > current_task->image_size) {
-					/* We also store the total size of the memory region used by the application */
-					current_task->image_size = shdr->sh_addr + shdr->sh_size - current_task->entry;
-				}
-				for (uintptr_t i = 0; i < shdr->sh_size; i += 0x1000) {
-					/* This doesn't care if we already allocated this page */
-					alloc_frame(get_page(shdr->sh_addr + i, 1, current_directory), 0, 1);
-				}
-				/* Copy the section into memory */
-				memcpy((void *)(shdr->sh_addr), (void *)((uintptr_t)header + shdr->sh_offset), shdr->sh_size);
-			}
-		}
-
-		/* Store the entry point to the code segment */
-		uintptr_t entry = (uintptr_t)header->e_entry;
-
-		/* Free the space we used for the ELF headers and files */
 		free(header);
 		close_fs(file);
+		kexit(127);
+	}
 
-		/* Go go go */
+	/* Load the loadable segments from the binary */
-		enter_user_jmp(entry, argc, argv);
+	for (uintptr_t x = 0; x < header->e_shentsize * header->e_shnum; x += header->e_shentsize) {
+		/* read a section header */
+		Elf32_Shdr * shdr = (Elf32_Shdr *)((uintptr_t)header + (header->e_shoff + x));
+		if (shdr->sh_addr) {
+			/* If this is a loadable section, load it up. */
+			if (shdr->sh_addr < current_task->entry) {
+				/* If this is the lowest entry point, store it for memory reasons */
+				current_task->entry = shdr->sh_addr;
+			}
+			if (shdr->sh_addr + shdr->sh_size - current_task->entry > current_task->image_size) {
+				/* We also store the total size of the memory region used by the application */
+				current_task->image_size = shdr->sh_addr + shdr->sh_size - current_task->entry;
+			}
+			for (uintptr_t i = 0; i < shdr->sh_size; i += 0x1000) {
+				/* This doesn't care if we already allocated this page */
+				alloc_frame(get_page(shdr->sh_addr + i, 1, current_directory), 0, 1);
+			}
+			/* Copy the section into memory */
+			memcpy((void *)(shdr->sh_addr), (void *)((uintptr_t)header + shdr->sh_offset), shdr->sh_size);
+		}
+	}
+
+	/* Store the entry point to the code segment */
+	uintptr_t entry = (uintptr_t)header->e_entry;
+
+	/* Free the space we used for the ELF headers and files */
+	free(header);
+	close_fs(file);
+
+	/* Go go go */
+	enter_user_jmp(entry, argc, argv);
 
 		/* We should never reach this code */
+	return -1;
+}
+
+int
+system(
+		char *  path, /* Path to the executable to run */
+		int     argc, /* Argument count (ie, /bin/echo hello world = 3) */
+		char ** argv  /* Argument strings (including executable path) */
+	) {
+	int child = fork();
+	if (child == 0) {
+		exec(path,argc,argv);
 		kexit(0x5ADFACE);
+		return -1;
 	} else {
-		/* We are emulating system(), so we need to wait for the child
+		/* We are system(), so we need to wait for the child
 		 * application to exit before we can continue. */
 		/* Get the child task. */
 		task_t * volatile child_task = gettask(child);
@@ -112,8 +122,6 @@ exec(
 		/* Grab the child's return value */
 		return child_task->retval;
 	}
-	/* Something went terribly wrong. */
-	return -1;
 }
 
 /*

kernel/core/shell.c

@@ -213,7 +213,7 @@ start_shell() {
 				if (tokenid < 2) {
 					continue;
 				}
-				int ret = exec(argv[1],tokenid - 1, &argv[1]);
+				int ret = system(argv[1],tokenid - 1, &argv[1]);
 				kprintf("Returned %d\n", ret);
 			} else if (!strcmp(cmd, "boredom")) {
 				int x = 30;
@@ -263,7 +263,7 @@ start_shell() {
 					kprintf("Unrecognized command: %s\n", cmd);
 				} else {
 					close_fs(chd);
-					exec(filename, tokenid, argv);
+					system(filename, tokenid, argv);
 				}
 				free(filename);
 			}

kernel/include/system.h

@@ -283,6 +283,7 @@ void enable_fpu();
 
 /* ELF */
 int exec( char *, int, char **);
+int system( char *, int, char **);
 
 /* Sytem Calls */
 void syscalls_install();

kernel/main.c

@@ -157,5 +157,21 @@ int main(struct multiboot *mboot, uint32_t mboot_mag, uintptr_t esp)
 
 	start_shell();
 
+	fork();
+
+	if (getpid() == 0) {
+		char * args[] = {
+			"/bin/yes",
+			"\033[1;32mA\033[0m"
+		};
+		exec("/bin/yes",2,args);
+	} else {
+		char * args[] = {
+			"/bin/yes",
+			"\033[1;31mB\033[0m"
+		};
+		exec("/bin/yes",2,args);
+	}
+
 	return 0;
 }