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android: fixed-point preload to resolve transitive .so deps #343

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android: fixed-point preload to resolve transitive .so deps #343

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66 changes: 58 additions & 8 deletions src/xrt/targets/common/target_plugin_loader.c
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Original file line number Diff line number Diff line change
Expand Up @@ -709,6 +709,7 @@ target_plugin_clear_preferred(void)
#include <dirent.h>
#include <dlfcn.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
Expand Down Expand Up @@ -904,12 +905,18 @@ get_runtime_lib_dir(char *out_dir, size_t out_size)
static void
preload_runtime_lib_dir(const char *lib_dir)
{
#define MAX_PRELOAD_CANDIDATES 64
char *names[MAX_PRELOAD_CANDIDATES];
int loaded[MAX_PRELOAD_CANDIDATES] = {0};
char *last_err[MAX_PRELOAD_CANDIDATES] = {0};
int n_candidates = 0;

DIR *d = opendir(lib_dir);
if (d == NULL) {
return;
}
struct dirent *de;
while ((de = readdir(d)) != NULL) {
while ((de = readdir(d)) != NULL && n_candidates < MAX_PRELOAD_CANDIDATES) {
if (de->d_type != DT_REG) {
continue;
}
Expand All @@ -928,16 +935,59 @@ preload_runtime_lib_dir(const char *lib_dir)
strncmp(name, "libopenxr_displayxr.so", 22) == 0) {
continue;
}
char path[PATH_MAX];
(void)snprintf(path, sizeof(path), "%s/%s", lib_dir, name);
void *h = dlopen(path, RTLD_LAZY | RTLD_LOCAL);
if (h == NULL) {
U_LOG_I("plugin loader: preload %s skipped: %s", name, dlerror());
} else {
U_LOG_I("plugin loader: preloaded %s", name);
names[n_candidates] = strdup(name);
if (names[n_candidates] == NULL) {
break;
}
n_candidates++;
}
closedir(d);

/* Fixed-point iteration: a vendor .so often has DT_NEEDED entries
* pointing at sibling .so files (e.g. CNSDK's libleiaSDK depends on
* libblink, which depends on libSNPE + liblicense_utils). readdir
* order is filesystem-dependent and may visit a dependent before
* its deps, so a single pass would fail to load it. Loop until a
* full pass produces no new successful loads. Worst case O(N²)
* dlopen attempts for N libs, but N is small (≤20) and dlopen of
* an already-loaded soinfo is essentially free. */
int total_loaded = 0;
bool progress = true;
while (progress) {
progress = false;
for (int i = 0; i < n_candidates; i++) {
if (loaded[i]) {
continue;
}
char path[PATH_MAX];
(void)snprintf(path, sizeof(path), "%s/%s", lib_dir, names[i]);
void *h = dlopen(path, RTLD_LAZY | RTLD_LOCAL);
if (h != NULL) {
U_LOG_I("plugin loader: preloaded %s", names[i]);
loaded[i] = 1;
total_loaded++;
progress = true;
free(last_err[i]);
last_err[i] = NULL;
} else {
/* Cache for final report; another pass might succeed. */
const char *err = dlerror();
free(last_err[i]);
last_err[i] = err ? strdup(err) : NULL;
}
}
}

for (int i = 0; i < n_candidates; i++) {
if (!loaded[i]) {
U_LOG_W("plugin loader: preload %s failed after fixed-point: %s", names[i],
last_err[i] ? last_err[i] : "(no dlerror)");
}
free(names[i]);
free(last_err[i]);
}
U_LOG_I("plugin loader: preload complete (%d/%d loaded)", total_loaded, n_candidates);
#undef MAX_PRELOAD_CANDIDATES
}

static const struct xrt_plugin_iface *
Expand Down
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