6329328daf
Instead of using and checking malloc'd error strings formatted with asprintf and passed through a pointer in function arguments, use a global thread-local statically allocated error buffer with functions to set and get it. This is more efficient, less error-prone, and easier to use than the old method, especially now that NM is larger (meaning that errors are returned through multiple layers) and parts of it are re-used in other things.
79 lines
2.4 KiB
C
79 lines
2.4 KiB
C
#define _GNU_SOURCE // asprintf, Dl_info, dladdr
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#include <dlfcn.h>
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#include <link.h>
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "failsafe.h"
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#include "util.h"
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struct nm_failsafe_t {
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char *orig;
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char *tmp;
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int delay;
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};
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nm_failsafe_t *nm_failsafe_create() {
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NM_LOG("failsafe: allocating memory");
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nm_failsafe_t *fs;
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NM_CHECK(NULL, (fs = calloc(1, sizeof(nm_failsafe_t))), "could not allocate memory");
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NM_LOG("failsafe: finding filenames");
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Dl_info info;
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NM_CHECK(NULL, dladdr(nm_failsafe_create, &info), "could not find own path");
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NM_CHECK(NULL, info.dli_fname, "dladdr did not return a filename");
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char *d = strrchr(info.dli_fname, '.');
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NM_CHECK(NULL, !(d && !strcmp(d, ".failsafe")), "lib was loaded from the failsafe for some reason");
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NM_CHECK(NULL, (fs->orig = realpath(info.dli_fname, NULL)), "could not resolve %s", info.dli_fname);
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NM_CHECK(NULL, asprintf(&fs->tmp, "%s.failsafe", fs->orig) != -1, "could not generate temp filename");
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NM_LOG("failsafe: ensuring own lib remains in memory even if it is dlclosed after being loaded with a dlopen");
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NM_CHECK(NULL, dlopen(fs->orig, RTLD_LAZY|RTLD_NODELETE), "could not dlopen self");
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NM_LOG("failsafe: renaming %s to %s", fs->orig, fs->tmp);
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NM_CHECK(NULL, !rename(fs->orig, fs->tmp), "could not rename lib");
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return fs;
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}
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static void *_nm_failsafe_destroy(void* _fs) {
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nm_failsafe_t *fs = (nm_failsafe_t*)(_fs);
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NM_LOG("failsafe: restoring after %d seconds", fs->delay);
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sleep(fs->delay);
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NM_LOG("failsafe: renaming %s to %s", fs->tmp, fs->orig);
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if (rename(fs->tmp, fs->orig))
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NM_LOG("error: could not rename lib");
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NM_LOG("failsafe: freeing memory");
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free(fs->orig);
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free(fs->tmp);
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free(fs);
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return NULL;
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}
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void nm_failsafe_destroy(nm_failsafe_t *fs, int delay) {
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fs->delay = delay;
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NM_LOG("failsafe: scheduling restore");
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pthread_attr_t attr;
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pthread_attr_init(&attr);
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pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
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pthread_t t;
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pthread_create(&t, &attr, _nm_failsafe_destroy, fs);
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const char name[16] = "nm_failsafe";
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pthread_setname_np(t, name);
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pthread_attr_destroy(&attr);
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}
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void nm_failsafe_uninstall(nm_failsafe_t *fs) {
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NM_LOG("failsafe: deleting %s", fs->tmp);
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unlink(fs->tmp);
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}
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