linux-user: Add generic env variable handling
Adds support for qemu to modify target process environment
variables using -E and -U commandline switches. This replaces
eventually the -drop-ld-preload flag.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6484 c046a42c-6fe2-441c-8c8c-71466251a162
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 732524f..2841120 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"
static const char *interp_prefix = CONFIG_QEMU_PREFIX;
@@ -2186,6 +2189,8 @@
"-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"
@@ -2195,6 +2200,12 @@
"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,
@@ -2229,8 +2240,8 @@
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();
@@ -2240,6 +2251,16 @@
/* 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(;;) {
@@ -2269,6 +2290,14 @@
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);
@@ -2301,7 +2330,7 @@
_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
@@ -2369,19 +2398,8 @@
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);
