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Unverified Commit cee55b59 by Christian Brauner
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rexec: remove envp parsing in favour of environ

My first attempt to simplify this and make it less costly focussed on the way constructors are called. I was under the impression that the ELF specification mandated that arg, argv, and actually even envp need to be passed to functions located in the .init_array section (aka "constructors"). Actually, the specifications is (cf. [2]): SHT_INIT_ARRAY This section contains an array of pointers to initialization functions, as described in ``Initialization and Termination Functions'' in Chapter 5. Each pointer in the array is taken as a parameterless procedure with a void return. which means that this becomes a libc specific decision. Glibc passes down those args, musl doesn't. So this approach can't work. However, we can at least remove the environment parsing part based on POSIX since [1] mandates that there should be an environ variable defined in unistd.h which provides access to the environment. See also the relevant Open Group specification [1]. [1]: http://pubs.opengroup.org/onlinepubs/9699919799/ [2]: http://www.sco.com/developers/gabi/latest/ch4.sheader.html#init_arraySigned-off-by: 's avatarChristian Brauner <christian.brauner@ubuntu.com>
parent 7a80606d
Showing with 18 additions and 22 deletions
src/lxc/rexec.c
......@@ -25,9 +25,12 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "config.h"
#include "file_utils.h"
#include "macro.h"
#include "memory_utils.h"
#include "raw_syscalls.h"
#include "string_utils.h"
#include "syscall_wrappers.h"
......@@ -60,35 +63,22 @@ static int push_vargs(char *data, int data_length, char ***output)
return num;
}
static int parse_exec_params(char ***argv, char ***envp)
static int parse_argv(char ***argv)
{
__do_free char *cmdline = NULL;
int ret;
char *cmdline = NULL, *env = NULL;
size_t cmdline_size, env_size;
size_t cmdline_size;
cmdline = file_to_buf("/proc/self/cmdline", &cmdline_size);
if (!cmdline)
goto on_error;
env = file_to_buf("/proc/self/environ", &env_size);
if (!env)
goto on_error;
return -1;
ret = push_vargs(cmdline, cmdline_size, argv);
if (ret <= 0)
goto on_error;
ret = push_vargs(env, env_size, envp);
if (ret <= 0)
goto on_error;
return -1;
steal_ptr(cmdline);
return 0;
on_error:
free(env);
free(cmdline);
return -1;
}
static int is_memfd(void)
......@@ -142,10 +132,16 @@ on_error:
errno = saved_errno;
}
/*
* Get cheap access to the environment. This must be declared by the user as
* mandated by POSIX. The definition is located in unistd.h.
*/
extern char **environ;
int lxc_rexec(const char *memfd_name)
{
int ret;
char **argv = NULL, **envp = NULL;
char **argv = NULL;
ret = is_memfd();
if (ret < 0 && ret == -ENOTRECOVERABLE) {
......@@ -157,7 +153,7 @@ int lxc_rexec(const char *memfd_name)
return 0;
}
ret = parse_exec_params(&argv, &envp);
ret = parse_argv(&argv);
if (ret < 0) {
fprintf(stderr,
"%s - Failed to parse command line parameters\n",
......@@ -165,7 +161,7 @@ int lxc_rexec(const char *memfd_name)
return -1;
}
lxc_rexec_as_memfd(argv, envp, memfd_name);
lxc_rexec_as_memfd(argv, environ, memfd_name);
fprintf(stderr, "%s - Failed to rexec as memfd\n", strerror(errno));
return -1;
}
......
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