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Merge pull request !40 from Thaodan/jb5181
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[sb2] Add support for posix_spawnp(). Contributes to JB#51819
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@Thaodan
Thaodan committed Dec 9, 2020
2 parents cb48390 + 5c02a1f commit c0c79d3
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Showing 3 changed files with 177 additions and 81 deletions.
4 changes: 2 additions & 2 deletions scratchbox2/execs/sb_exec.c
View file
Expand Up @@ -12,8 +12,8 @@
* Brief description of the algorithm follows:
*
* 0. When an application wants to execute another program, it makes a call
* to one of execl(), execle(), execlp(), execv(), execve(), execvp() or
* posix_spawn().
* to one of execl(), execle(), execlp(), execv(), execve(), execvp(),
* posix_spawn() or posix_spawnp().
* That call will be handled by one of the gate functions in
* preload/libsb2.c. Eventually, the gate function will call "do_exec()"
* from this file; do_exec() calls prepare_exec() and that is the place
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250 changes: 171 additions & 79 deletions scratchbox2/preload/execgates.c
View file
Expand Up @@ -32,6 +32,7 @@
#include <ctype.h>
#include <stdlib.h>
#include <signal.h>
#include <errno.h>
#include "libsb2.h"
#include "exported.h"

Expand Down Expand Up @@ -363,6 +364,69 @@ static char **create_argv_for_script_exec(const char *file, char *const argv[])
return(new_argv);
}

static int search_path(const char *file, char **ret)
{
char *name;
char *path;
size_t len;
size_t pathlen;
int got_eacces = 0;
int retval = -1;

char *pathenv = getenv ("PATH");
if (pathenv) {
path = strdup(pathenv);
} else {
/* There is no `PATH' in the environment.
The default search path is the current directory
followed by the path `confstr' returns for `_CS_PATH'. */
len = confstr (_CS_PATH, (char *) NULL, 0);
path = (char *) malloc (1 + len);
path[0] = ':';
(void) confstr (_CS_PATH, path + 1, len);
}

len = strlen(file) + 1;
pathlen = strlen(path);
name = alloca (pathlen + len + 1);
/* Copy the file name at the top. */
name = (char *) memcpy (name + pathlen + 1, file, len);
/* And add the slash. */
*--name = '/';

const char *p = path;
do {
char *startp;
const char *old_p = p;
p = sb2_strchrnul (old_p, ':');

if (p == old_p) {
/* Two adjacent colons, or a colon at the beginning or the end
of `PATH' means to search the current directory. */
startp = (char *) name + 1;
} else {
startp = (char *) memcpy (name - (p - old_p), old_p, p - old_p);
}

if (access(startp, X_OK) == 0) {
int startp_len = strlen(startp)+1;
*ret = malloc(startp_len);
memcpy(*ret, startp, startp_len);

retval = 0;
goto out;
} else {
if (errno == EACCES)
got_eacces = 1;
}
} while (*p++ != '\0');

if (got_eacces)
errno = EACCES;
out:
free(path);
return retval;
}

static int do_execvep(
int *result_errno_ptr,
Expand All @@ -388,93 +452,102 @@ static int do_execvep(
}
return(-1);
} else {
int got_eacces = 0;
const char *p;
const char *path;
char *name;
size_t len;
size_t pathlen;

path = getenv ("PATH");
if (path) path = strdup(path);
if (path == NULL) {
/* There is no `PATH' in the environment.
The default search path is the current directory
followed by the path `confstr' returns for `_CS_PATH'. */
char *new_path;
len = confstr (_CS_PATH, (char *) NULL, 0);
new_path = (char *) alloca (1 + len);
new_path[0] = ':';
(void) confstr (_CS_PATH, new_path + 1, len);
path = new_path;
}

len = strlen (file) + 1;
pathlen = strlen (path);
name = alloca (pathlen + len + 1);
/* Copy the file name at the top. */
name = (char *) memcpy (name + pathlen + 1, file, len);
/* And add the slash. */
*--name = '/';

p = path;
do {
char *startp;

path = p;
p = sb2_strchrnul (path, ':');

if (p == path) {
/* Two adjacent colons, or a colon at the beginning or the end
of `PATH' means to search the current directory. */
startp = name + 1;
} else {
startp = (char *) memcpy (name - (p - path), path, p - path);
}

/* Try to execute this name. If it works, execv will not return. */
execve_gate (result_errno_ptr, NULL, realfnname, startp, argv, envp);
char *startp = NULL;

if (search_path(file, &startp) != 0) {
/* We tried every element and none of them worked. */
/* At least one failure was due to permissions, so report that
error. */
if (errno == EACCES)
*result_errno_ptr = EACCES;
free(startp);
return -1;
}

/* Try to execute this name. If it works, execv will not return. */
execve_gate (result_errno_ptr, NULL, realfnname, startp, argv, envp);

if (*result_errno_ptr == ENOEXEC) {
char **new_argv = create_argv_for_script_exec(
startp, argv);
execve_gate (result_errno_ptr, NULL, realfnname, new_argv[0], new_argv, envp);
free(new_argv);
}

free(startp);
}

if (*result_errno_ptr == ENOEXEC) {
char **new_argv = create_argv_for_script_exec(
startp, argv);
execve_gate (result_errno_ptr, NULL, realfnname, new_argv[0], new_argv, envp);
free(new_argv);
}
/* Return the error from the last attempt (probably ENOENT). */
return -1;
}

switch (*result_errno_ptr) {
case EACCES:
/* Record the we got a `Permission denied' error. If we end
up finding no executable we can use, we want to diagnose
that we did find one but were denied access. */
got_eacces = 1;
case ENOENT:
case ESTALE:
case ENOTDIR:
/* Those errors indicate the file is missing or not executable
by us, in which case we want to just try the next path
directory. */
break;

default:
/* Some other error means we found an executable file, but
something went wrong executing it; return the error to our
caller. */
return -1;
}
} while (*p++ != '\0');
static int do_posix_spawnp(
int *result_errno_ptr,
const char *realfnname, pid_t *pid, const char *file,
const posix_spawn_file_actions_t *file_actions,
const posix_spawnattr_t *attrp,
char *const *argv, char *const *envp)
{
int result;
if (*file == '\0') {
/* We check the simple case first. */
*result_errno_ptr = ENOENT;
return ENOENT;
}

/* We tried every element and none of them worked. */
if (got_eacces)
/* At least one failure was due to permissions, so report that
error. */
*result_errno_ptr = EACCES;
if (strchr (file, '/') != NULL) {
/* Try to execute this name. If it works, execv will not return. */
result = do_posix_spawn(result_errno_ptr,
realfnname, pid, file,
file_actions, attrp,
argv, envp);

if (*result_errno_ptr == ENOEXEC) {
char **new_argv = create_argv_for_script_exec(
file, argv);
result = do_posix_spawn(result_errno_ptr,
realfnname, pid, new_argv[0],
file_actions, attrp,
new_argv, envp);
free(new_argv);
}

return(result);
} else {
char *startp = NULL;

if (search_path(file, &startp) != 0) {
/* We tried every element and none of them worked. */
/* At least one failure was due to permissions,
* so report error. */
if (errno == EACCES)
*result_errno_ptr = EACCES;
free(startp);
return -1;
}


result = do_posix_spawn(result_errno_ptr,
realfnname, pid, startp,
file_actions, attrp, argv, envp);

if (*result_errno_ptr == ENOEXEC) {
char **new_argv = create_argv_for_script_exec(
startp, argv);
result = do_posix_spawn(result_errno_ptr,
realfnname, pid, new_argv[0],
file_actions, attrp,
new_argv, envp);
free(new_argv);
}
free(startp);
}

/* Return the error from the last attempt (probably ENOENT). */
return -1;
return result;
}


int sb_execvep(
const char *file,
char *const argv [],
Expand Down Expand Up @@ -531,6 +604,25 @@ int posix_spawn_gate(
file_actions, attrp, argv, envp);
}

int posix_spawnp_gate(
int *result_errno_ptr,
int (*real_posix_spawnp_ptr)(pid_t *pid, const char *file,
const posix_spawn_file_actions_t *file_actions,
const posix_spawnattr_t *attrp,
char *const argv[], char *const envp[]),
const char *realfnname,
pid_t *pid,
const char *file,
const posix_spawn_file_actions_t *file_actions,
const posix_spawnattr_t *attrp,
char *const argv[],
char *const envp[])
{
(void)real_posix_spawnp_ptr;
return do_posix_spawnp(result_errno_ptr, realfnname, pid, file,
file_actions, attrp, argv, envp);
}

/* SETRLIMIT_ARG1_TYPE is defined in interface.master */

int setrlimit_gate(
Expand Down
4 changes: 4 additions & 0 deletions scratchbox2/preload/interface.master
View file
Expand Up @@ -115,6 +115,10 @@ GATE: int posix_spawn (pid_t *pid, const char *path, \
const posix_spawn_file_actions_t *file_actions, \
const posix_spawnattr_t *attrp, \
char *const argv[], char *const envp[])
GATE: int posix_spawnp (pid_t *pid, const char *file, \
const posix_spawn_file_actions_t *file_actions, \
const posix_spawnattr_t *attrp, \
char *const argv[], char *const envp[])

GATE: char * getcwd (char *buf, size_t size) : \
returns_string create_nomap_nolog_version
Expand Down

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