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/*
* Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Hyra nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/sched.h>
#include <sys/system.h>
#include <sys/errno.h>
#include <sys/vfs.h>
#include <sys/exec.h>
#include <sys/filedesc.h>
#include <sys/signal.h>
#include <sys/loader.h>
#include <sys/cdefs.h>
#include <vm/dynalloc.h>
#include <sys/syslog.h>
#include <string.h>
__MODULE_NAME("exec");
__KERNEL_META("$Hyra$: kern_exec.c, Ian Marco Moffett, "
"exec() implementation");
#define ARG_MAX 1024
/*
* Allocates a buffer in in `res' and fetches
* the args from `argv'
*
* @argv: User argv
* @res: Exec args result.
*
* XXX: res->argp is dynamically allocated, remember
* to free it!
*/
static int
exec_get_args(char **argv, struct exec_args *res)
{
const size_t ARG_LEN = sizeof(char) * ARG_MAX;
char *argp = NULL;
void *tmp;
struct proc *td;
size_t argp_len = 0;
if (res == NULL)
return -EINVAL;
/* Allocate argp */
res->argp = dynalloc(ARG_LEN);
if (res->argp == NULL)
return -ENOMEM;
td = this_td();
res->vas = td->addrsp;
/* Read argv */
copyin((uintptr_t)argv, &argp, sizeof(char *));
for (;;) {
if (argp == NULL) {
res->argp[argp_len] = NULL;
break;
}
/* Fetch this arg and get next argp */
copyinstr((uintptr_t)argp, res->argp[argp_len++], ARG_MAX);
copyin((uintptr_t)++argv, &argp, sizeof(char *));
/* Try to resize the argp buffer */
tmp = dynrealloc(res->argp, ARG_LEN * (argp_len + 1));
if (tmp == NULL) {
dynfree(res->argp);
return -ENOMEM;
}
res->argp = tmp;
}
return 0;
}
/*
* Reset the stack of the process.
*
* @td: Target thread.
* @args: Exec args.
*
* Returns the new stack pointer.
*/
static uintptr_t
exec_set_stack(struct proc *td, struct exec_args args)
{
struct vm_range *stack_range;
uintptr_t stack_top, sp;
stack_range = &td->addr_range[ADDR_RANGE_STACK];
stack_top = stack_range->start + (PROC_STACK_SIZE);
sp = loader_init_stack((void *)stack_top, args);
return sp;
}
/*
* execv() implementation.
*
* @pathname: Path of file to execute.
* @argv: Args.
* @sp_res: Pointer to new stack pointer
*/
static int
execv(char *pathname, char **argv, uintptr_t *sp_res)
{
char *bin = NULL;
struct filedesc *filedes;
struct vm_range *exec_range;
struct exec_args args;
struct proc *td = this_td();
int fd, ret = 0;
int status;
size_t bin_size;
if ((status = exec_get_args(argv, &args)) != 0)
return status;
spinlock_acquire(&td->lock);
fd = open(pathname, O_RDONLY);
if (fd < 0) {
ret = -ENOENT;
goto done;
}
filedes = fd_from_fdnum(td, fd);
if (__unlikely(filedes == NULL)) {
/*
* Should not happen. The kernel might be in some
* erroneous state.
*/
ret = -EIO;
goto done;
}
lseek(fd, 0, SEEK_END);
bin_size = filedes->offset;
lseek(fd, 0, SEEK_SET);
/* Allocate memory for the binary */
bin = dynalloc(bin_size);
if (bin == NULL) {
ret = -ENOMEM;
goto done;
}
/* Read-in the binary */
if ((status = read(fd, bin, bin_size)) < 0) {
ret = status;
goto done;
}
/*
* Unload the current process image. After we do this,
* we cannot return in this state until we replace it.
*
* XXX: This is one of the last things we do in case of
* errors.
*/
exec_range = &td->addr_range[ADDR_RANGE_EXEC];
loader_unload(td->addrsp, exec_range);
/*
* Now we try to load the new program and hope everything
* works... If something goes wrong here then we'll be forced
* to send a SIGSEGV to the thread.
*/
status = loader_load(td->addrsp, bin, &args.auxv, 0, NULL, exec_range);
if (status != 0) {
/* Well shit */
KERR("Failed to load new process image\n");
signal_raise(td, SIGSEGV);
for (;;);
}
*sp_res = exec_set_stack(td, args);
set_frame_ip(td->tf, args.auxv.at_entry);
done:
/* We are done, cleanup and release the thread */
if (bin != NULL) dynfree(bin);
fd_close_fdnum(td, fd);
dynfree(args.argp);
spinlock_release(&td->lock);
return ret;
}
/*
* Arg0: Pathname
* Arg1: Argv
*/
uint64_t
sys_execv(struct syscall_args *args)
{
uintptr_t sp;
char pathname[PATH_MAX];
char **argv = (char **)args->arg1;
int status;
struct proc *td = this_td();
copyinstr(args->arg0, pathname, PATH_MAX);
if ((status = execv(pathname, argv, &sp)) != 0)
return status;
args->ip = get_frame_ip(td->tf);
args->sp = sp;
return 0;
}
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