1 files changed, 108 insertions, 0 deletions
diff --git a/system_cmds/gcore.tproj/dyld_shared_cache.c b/system_cmds/gcore.tproj/dyld_shared_cache.c
new file mode 100644
index 0000000..0e21163
--- /dev/null
+++ b/system_cmds/gcore.tproj/dyld_shared_cache.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2016 Apple Inc.  All rights reserved.
+ */
+
+#include "options.h"
+#include "dyld_shared_cache.h"
+#include "utils.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <strings.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fts.h>
+#include <fcntl.h>
+#include <assert.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <TargetConditionals.h>
+
+static const size_t dyld_cache_header_size = sizeof (struct copied_dyld_cache_header);
+
+/*
+ * The shared cache must both contain the magic ID and
+ * match the uuid we discovered via dyld's information.
+ * Assumes that the dyld_cache_header grows in a binary compatible fashion.
+ */
+bool
+get_uuid_from_shared_cache_mapping(const void *addr, size_t size, uuid_t out)
+{
+    const struct copied_dyld_cache_header *ch = addr;
+    if (size < sizeof (*ch))
+        return false;
+    static const char prefix[] = "dyld_v";
+    if (strncmp(ch->magic, prefix, strlen(prefix)) != 0)
+        return false;
+    uuid_copy(out, ch->uuid);
+    return true;
+}
+
+/*
+ * Look in the known places to see if we can find this one ..
+ */
+char *
+shared_cache_filename(const uuid_t uu)
+{
+    assert(!uuid_is_null(uu));
+    static char *sc_argv[] = {
+#if TARGET_OS_OSX
+        "/System/Library/dyld",
+#elif TARGET_OS_IPHONE
+        "/System/Library/Caches/com.apple.dyld",
+#else
+#error undefined
+#endif
+        NULL
+    };
+    char *nm = NULL;
+    FTS *fts = fts_open(sc_argv, FTS_NOCHDIR | FTS_LOGICAL | FTS_XDEV, NULL);
+    if (NULL != fts) {
+        FTSENT *fe;
+        while (NULL != (fe = fts_read(fts))) {
+            if ((fe->fts_info & FTS_F) == 0 ||
+                (fe->fts_info & FTS_ERR) != 0)
+                continue;
+
+            static const char prefix[] = "dyld_shared_cache_";
+            if (strncmp(fe->fts_name, prefix, strlen(prefix)) != 0)
+                continue;
+
+            if (fe->fts_statp->st_size < (off_t)dyld_cache_header_size)
+                continue;
+
+            int d = open(fe->fts_accpath, O_RDONLY);
+            if (-1 == d) {
+                if (OPTIONS_DEBUG(opt, 1))
+                    printf("%s: cannot open - %s\n", fe->fts_accpath, strerror(errno));
+                continue;
+            }
+            void *addr = mmap(NULL, dyld_cache_header_size, PROT_READ, MAP_PRIVATE, d, 0);
+            close(d);
+            if ((void *)-1 == addr) {
+                if (OPTIONS_DEBUG(opt, 1))
+                    printf("%s: cannot mmap - %s\n", fe->fts_accpath, strerror(errno));
+                continue;
+            }
+            uuid_t scuuid;
+            uuid_clear(scuuid);
+            if (get_uuid_from_shared_cache_mapping(addr, dyld_cache_header_size, scuuid)) {
+                if (uuid_compare(uu, scuuid) == 0)
+                    nm = strdup(fe->fts_accpath);
+                else if (OPTIONS_DEBUG(opt, 3)) {
+                    uuid_string_t scstr;
+                    uuid_unparse_lower(scuuid, scstr);
+                    printf("%s: shared cache mismatch (%s)\n", fe->fts_accpath, scstr);
+                }
+            }
+            munmap(addr, dyld_cache_header_size);
+            if (NULL != nm)
+                break;
+        }
+    }
+    if (fts)
+        fts_close(fts);
+    return nm;
+}