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Re: [Qemu-devel] [PATCH] linux-user: Add generic env variable handling
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH] linux-user: Add generic env variable handling |
Date: |
Fri, 30 Jan 2009 20:52:15 +0100 |
User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Mon, Jan 19, 2009 at 05:30:15PM +0200, Riku Voipio wrote:
> Adds support for qemu to modify target process environment
> variables using -E and -U commandline switches. This replaces
> eventually the -drop-ld-preload flag.
>
> From: Mika Westerberg
>
> Signed-off-by: Riku Voipio <address@hidden>
> ---
Thanks, applied.
> Makefile.target | 2 +-
> linux-user/envlist.c | 247
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> linux-user/envlist.h | 22 +++++
> linux-user/main.c | 50 +++++++---
> 4 files changed, 304 insertions(+), 17 deletions(-)
> create mode 100644 linux-user/envlist.c
> create mode 100644 linux-user/envlist.h
>
> diff --git a/Makefile.target b/Makefile.target
> index fcaf4ec..a736343 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -373,7 +373,7 @@ CFLAGS+=-p
> endif
>
> OBJS= main.o syscall.o strace.o mmap.o signal.o path.o thunk.o \
> - elfload.o linuxload.o uaccess.o
> + elfload.o linuxload.o uaccess.o envlist.o
> LIBS+= $(AIOLIBS)
> ifdef TARGET_HAS_BFLT
> OBJS+= flatload.o
> diff --git a/linux-user/envlist.c b/linux-user/envlist.c
> new file mode 100644
> index 0000000..e13c2d3
> --- /dev/null
> +++ b/linux-user/envlist.c
> @@ -0,0 +1,247 @@
> +#include <sys/queue.h>
> +
> +#include <assert.h>
> +#include <errno.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +#include "envlist.h"
> +
> +struct envlist_entry {
> + const char *ev_var; /* actual env value */
> + LIST_ENTRY(envlist_entry) ev_link;
> +};
> +
> +struct envlist {
> + LIST_HEAD(, envlist_entry) el_entries; /* actual entries */
> + size_t el_count; /* number of entries */
> +};
> +
> +static int envlist_parse(envlist_t *envlist,
> + const char *env, int (*)(envlist_t *, const char *));
> +
> +/*
> + * Allocates new envlist and returns pointer to that or
> + * NULL in case of error.
> + */
> +envlist_t *
> +envlist_create(void)
> +{
> + envlist_t *envlist;
> +
> + if ((envlist = malloc(sizeof (*envlist))) == NULL)
> + return (NULL);
> +
> + LIST_INIT(&envlist->el_entries);
> + envlist->el_count = 0;
> +
> + return (envlist);
> +}
> +
> +/*
> + * Releases given envlist and its entries.
> + */
> +void
> +envlist_free(envlist_t *envlist)
> +{
> + struct envlist_entry *entry;
> +
> + assert(envlist != NULL);
> +
> + while (envlist->el_entries.lh_first != NULL) {
> + entry = envlist->el_entries.lh_first;
> + LIST_REMOVE(entry, ev_link);
> +
> + free((char *)entry->ev_var);
> + free(entry);
> + }
> + free(envlist);
> +}
> +
> +/*
> + * Parses comma separated list of set/modify environment
> + * variable entries and updates given enlist accordingly.
> + *
> + * For example:
> + * envlist_parse(el, "HOME=foo,SHELL=/bin/sh");
> + *
> + * inserts/sets environment variables HOME and SHELL.
> + *
> + * Returns 0 on success, errno otherwise.
> + */
> +int
> +envlist_parse_set(envlist_t *envlist, const char *env)
> +{
> + return (envlist_parse(envlist, env, &envlist_setenv));
> +}
> +
> +/*
> + * Parses comma separated list of unset environment variable
> + * entries and removes given variables from given envlist.
> + *
> + * Returns 0 on success, errno otherwise.
> + */
> +int
> +envlist_parse_unset(envlist_t *envlist, const char *env)
> +{
> + return (envlist_parse(envlist, env, &envlist_unsetenv));
> +}
> +
> +/*
> + * Parses comma separated list of set, modify or unset entries
> + * and calls given callback for each entry.
> + *
> + * Returns 0 in case of success, errno otherwise.
> + */
> +static int
> +envlist_parse(envlist_t *envlist, const char *env,
> + int (*callback)(envlist_t *, const char *))
> +{
> + char *tmpenv, *envvar;
> + char *envsave = NULL;
> +
> + assert(callback != NULL);
> +
> + if ((envlist == NULL) || (env == NULL))
> + return (EINVAL);
> +
> + /*
> + * We need to make temporary copy of the env string
> + * as strtok_r(3) modifies it while it tokenizes.
> + */
> + if ((tmpenv = strdup(env)) == NULL)
> + return (errno);
> +
> + envvar = strtok_r(tmpenv, ",", &envsave);
> + while (envvar != NULL) {
> + if ((*callback)(envlist, envvar) != 0) {
> + free(tmpenv);
> + return (errno);
> + }
> + envvar = strtok_r(NULL, ",", &envsave);
> + }
> +
> + free(tmpenv);
> + return (0);
> +}
> +
> +/*
> + * Sets environment value to envlist in similar manner
> + * than putenv(3).
> + *
> + * Returns 0 in success, errno otherwise.
> + */
> +int
> +envlist_setenv(envlist_t *envlist, const char *env)
> +{
> + struct envlist_entry *entry = NULL;
> + const char *eq_sign;
> + size_t envname_len;
> +
> + if ((envlist == NULL) || (env == NULL))
> + return (EINVAL);
> +
> + /* find out first equals sign in given env */
> + if ((eq_sign = strchr(env, '=')) == NULL)
> + return (EINVAL);
> + envname_len = eq_sign - env + 1;
> +
> + /*
> + * If there already exists variable with given name
> + * we remove and release it before allocating a whole
> + * new entry.
> + */
> + for (entry = envlist->el_entries.lh_first; entry != NULL;
> + entry = entry->ev_link.le_next) {
> + if (strncmp(entry->ev_var, env, envname_len) == 0)
> + break;
> + }
> +
> + if (entry != NULL) {
> + LIST_REMOVE(entry, ev_link);
> + free((char *)entry->ev_var);
> + free(entry);
> + } else {
> + envlist->el_count++;
> + }
> +
> + if ((entry = malloc(sizeof (*entry))) == NULL)
> + return (errno);
> + if ((entry->ev_var = strdup(env)) == NULL) {
> + free(entry);
> + return (errno);
> + }
> + LIST_INSERT_HEAD(&envlist->el_entries, entry, ev_link);
> +
> + return (0);
> +}
> +
> +/*
> + * Removes given env value from envlist in similar manner
> + * than unsetenv(3). Returns 0 in success, errno otherwise.
> + */
> +int
> +envlist_unsetenv(envlist_t *envlist, const char *env)
> +{
> + struct envlist_entry *entry;
> + size_t envname_len;
> +
> + if ((envlist == NULL) || (env == NULL))
> + return (EINVAL);
> +
> + /* env is not allowed to contain '=' */
> + if (strchr(env, '=') != NULL)
> + return (EINVAL);
> +
> + /*
> + * Find out the requested entry and remove
> + * it from the list.
> + */
> + envname_len = strlen(env);
> + for (entry = envlist->el_entries.lh_first; entry != NULL;
> + entry = entry->ev_link.le_next) {
> + if (strncmp(entry->ev_var, env, envname_len) == 0)
> + break;
> + }
> + if (entry != NULL) {
> + LIST_REMOVE(entry, ev_link);
> + free((char *)entry->ev_var);
> + free(entry);
> +
> + envlist->el_count--;
> + }
> + return (0);
> +}
> +
> +/*
> + * Returns given envlist as array of strings (in same form that
> + * global variable environ is). Caller must free returned memory
> + * by calling free(3) for each element and for the array. Returned
> + * array and given envlist are not related (no common references).
> + *
> + * If caller provides count pointer, number of items in array is
> + * stored there. In case of error, NULL is returned and no memory
> + * is allocated.
> + */
> +char **
> +envlist_to_environ(const envlist_t *envlist, size_t *count)
> +{
> + struct envlist_entry *entry;
> + char **env, **penv;
> +
> + penv = env = malloc((envlist->el_count + 1) * sizeof (char *));
> + if (env == NULL)
> + return (NULL);
> +
> + for (entry = envlist->el_entries.lh_first; entry != NULL;
> + entry = entry->ev_link.le_next) {
> + *(penv++) = strdup(entry->ev_var);
> + }
> + *penv = NULL; /* NULL terminate the list */
> +
> + if (count != NULL)
> + *count = envlist->el_count;
> +
> + return (env);
> +}
> diff --git a/linux-user/envlist.h b/linux-user/envlist.h
> new file mode 100644
> index 0000000..e76d4a1
> --- /dev/null
> +++ b/linux-user/envlist.h
> @@ -0,0 +1,22 @@
> +#ifndef ENVLIST_H
> +#define ENVLIST_H
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +typedef struct envlist envlist_t;
> +
> +extern envlist_t *envlist_create(void);
> +extern void envlist_free(envlist_t *);
> +extern int envlist_setenv(envlist_t *, const char *);
> +extern int envlist_unsetenv(envlist_t *, const char *);
> +extern int envlist_parse_set(envlist_t *, const char *);
> +extern int envlist_parse_unset(envlist_t *, const char *);
> +extern char **envlist_to_environ(const envlist_t *, size_t *);
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* ENVLIST_H */
> diff --git a/linux-user/main.c b/linux-user/main.c
> index 2ffe244..21a0626 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -32,6 +32,9 @@
> /* For tb_lock */
> #include "exec-all.h"
>
> +
> +#include "envlist.h"
> +
> #define DEBUG_LOGFILE "/tmp/qemu.log"
>
> char *exec_path;
> @@ -2190,6 +2193,8 @@ static void usage(void)
> "-s size set the stack size in bytes (default=%ld)\n"
> "-cpu model select CPU (-cpu ? for list)\n"
> "-drop-ld-preload drop LD_PRELOAD for target process\n"
> + "-E var=value sets/modifies targets environment
> variable(s)\n"
> + "-U var unsets targets environment variable(s)\n"
> "\n"
> "Debug options:\n"
> "-d options activate log (logfile=%s)\n"
> @@ -2199,6 +2204,12 @@ static void usage(void)
> "Environment variables:\n"
> "QEMU_STRACE Print system calls and arguments similar to
> the\n"
> " 'strace' program. Enable by setting to any
> value.\n"
> + "You can use -E and -U options to set/unset environment
> variables\n"
> + "for target process. It is possible to provide several
> variables\n"
> + "by repeating the option. For example:\n"
> + " -E var1=val2 -E var2=val2 -U LD_PRELOAD -U LD_DEBUG\n"
> + "Note that if you provide several changes to single variable\n"
> + "last change will stay in effect.\n"
> ,
> TARGET_ARCH,
> interp_prefix,
> @@ -2233,8 +2244,8 @@ int main(int argc, char **argv, char **envp)
> int optind;
> const char *r;
> int gdbstub_port = 0;
> - int drop_ld_preload = 0, environ_count = 0;
> - char **target_environ, **wrk, **dst;
> + char **target_environ, **wrk;
> + envlist_t *envlist = NULL;
>
> if (argc <= 1)
> usage();
> @@ -2244,6 +2255,16 @@ int main(int argc, char **argv, char **envp)
> /* init debug */
> cpu_set_log_filename(DEBUG_LOGFILE);
>
> + if ((envlist = envlist_create()) == NULL) {
> + (void) fprintf(stderr, "Unable to allocate envlist\n");
> + exit(1);
> + }
> +
> + /* add current environment into the list */
> + for (wrk = environ; *wrk != NULL; wrk++) {
> + (void) envlist_setenv(envlist, *wrk);
> + }
> +
> cpu_model = NULL;
> optind = 1;
> for(;;) {
> @@ -2273,6 +2294,14 @@ int main(int argc, char **argv, char **envp)
> _exit(1);
> }
> cpu_set_log(mask);
> + } else if (!strcmp(r, "E")) {
> + r = argv[optind++];
> + if (envlist_setenv(envlist, r) != 0)
> + usage();
> + } else if (!strcmp(r, "U")) {
> + r = argv[optind++];
> + if (envlist_unsetenv(envlist, r) != 0)
> + usage();
> } else if (!strcmp(r, "s")) {
> r = argv[optind++];
> x86_stack_size = strtol(r, (char **)&r, 0);
> @@ -2305,7 +2334,7 @@ int main(int argc, char **argv, char **envp)
> _exit(1);
> }
> } else if (!strcmp(r, "drop-ld-preload")) {
> - drop_ld_preload = 1;
> + (void) envlist_unsetenv(envlist, "LD_PRELOAD");
> } else if (!strcmp(r, "strace")) {
> do_strace = 1;
> } else
> @@ -2374,19 +2403,8 @@ int main(int argc, char **argv, char **envp)
> do_strace = 1;
> }
>
> - wrk = environ;
> - while (*(wrk++))
> - environ_count++;
> -
> - target_environ = malloc((environ_count + 1) * sizeof(char *));
> - if (!target_environ)
> - abort();
> - for (wrk = environ, dst = target_environ; *wrk; wrk++) {
> - if (drop_ld_preload && !strncmp(*wrk, "LD_PRELOAD=", 11))
> - continue;
> - *(dst++) = strdup(*wrk);
> - }
> - *dst = NULL; /* NULL terminate target_environ */
> + target_environ = envlist_to_environ(envlist, NULL);
> + envlist_free(envlist);
>
> if (loader_exec(filename, argv+optind, target_environ, regs, info) != 0)
> {
> printf("Error loading %s\n", filename);
> --
> 1.5.6.5
>
>
> --
> "rm -rf" only sounds scary if you don't have backups
>
>
>
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net