add a one-argument version of package_extract_file

Add a version of package_extract_file that returns the file data as
its return value (to be consumed by some other edify function that
expects to receive a bunch of binary data as an argument).  Lets us
avoid having two copies of a big file in memory (extracting it into
/tmp, which is a ramdisk, and then having something load it into
memory) when doing things like radio updates.

Change-Id: Ie26ece5fbae457eb0ddcd8a13d74d78a769fbc70

minzip/Zip.c

@@ -810,6 +810,43 @@ bool mzExtractZipEntryToFile(const ZipArchive *pArchive,
     return true;
 }
 
+typedef struct {
+    unsigned char* buffer;
+    long len;
+} BufferExtractCookie;
+
+static bool bufferProcessFunction(const unsigned char *data, int dataLen,
+    void *cookie) {
+    BufferExtractCookie *bec = (BufferExtractCookie*)cookie;
+
+    memmove(bec->buffer, data, dataLen);
+    bec->buffer += dataLen;
+    bec->len -= dataLen;
+
+    return true;
+}
+
+/*
+ * Uncompress "pEntry" in "pArchive" to buffer, which must be large
+ * enough to hold mzGetZipEntryUncomplen(pEntry) bytes.
+ */
+bool mzExtractZipEntryToBuffer(const ZipArchive *pArchive,
+    const ZipEntry *pEntry, unsigned char *buffer)
+{
+    BufferExtractCookie bec;
+    bec.buffer = buffer;
+    bec.len = mzGetZipEntryUncompLen(pEntry);
+
+    bool ret = mzProcessZipEntryContents(pArchive, pEntry,
+        bufferProcessFunction, (void*)&bec);
+    if (!ret || bec.len != 0) {
+        LOGE("Can't extract entry to memory buffer.\n");
+        return false;
+    }
+    return true;
+}
+
+
 /* Helper state to make path translation easier and less malloc-happy.
  */
 typedef struct {

minzip/Zip.h

@@ -168,6 +168,13 @@ bool mzIsZipEntryIntact(const ZipArchive *pArchive, const ZipEntry *pEntry);
 bool mzExtractZipEntryToFile(const ZipArchive *pArchive,
     const ZipEntry *pEntry, int fd);
 
+/*
+ * Inflate and write an entry to a memory buffer, which must be long
+ * enough to hold mzGetZipEntryUncomplen(pEntry) bytes.
+ */
+bool mzExtractZipEntryToBuffer(const ZipArchive *pArchive,
+    const ZipEntry *pEntry, unsigned char* buffer);
+
 /*
  * Inflate all entries under zipDir to the directory specified by
  * targetDir, which must exist and be a writable directory.

updater/install.c

@@ -315,37 +315,82 @@ char* PackageExtractDirFn(const char* name, State* state,
 
 
 // package_extract_file(package_path, destination_path)
+//   or
+// package_extract_file(package_path)
+//   to return the entire contents of the file as the result of this
+//   function (the char* returned points to a long giving the length
+//   followed by that many bytes of data).
 char* PackageExtractFileFn(const char* name, State* state,
                            int argc, Expr* argv[]) {
-    if (argc != 2) {
-        return ErrorAbort(state, "%s() expects 2 args, got %d", name, argc);
+    if (argc != 1 && argc != 2) {
+        return ErrorAbort(state, "%s() expects 1 or 2 args, got %d",
+                          name, argc);
     }
-    char* zip_path;
-    char* dest_path;
-    if (ReadArgs(state, argv, 2, &zip_path, &dest_path) < 0) return NULL;
-
     bool success = false;
+    if (argc == 2) {
+        // The two-argument version extracts to a file.
 
-    ZipArchive* za = ((UpdaterInfo*)(state->cookie))->package_zip;
-    const ZipEntry* entry = mzFindZipEntry(za, zip_path);
-    if (entry == NULL) {
-        fprintf(stderr, "%s: no %s in package\n", name, zip_path);
-        goto done;
+        char* zip_path;
+        char* dest_path;
+        if (ReadArgs(state, argv, 2, &zip_path, &dest_path) < 0) return NULL;
+
+        ZipArchive* za = ((UpdaterInfo*)(state->cookie))->package_zip;
+        const ZipEntry* entry = mzFindZipEntry(za, zip_path);
+        if (entry == NULL) {
+            fprintf(stderr, "%s: no %s in package\n", name, zip_path);
+            goto done2;
+        }
+
+        FILE* f = fopen(dest_path, "wb");
+        if (f == NULL) {
+            fprintf(stderr, "%s: can't open %s for write: %s\n",
+                    name, dest_path, strerror(errno));
+            goto done2;
+        }
+        success = mzExtractZipEntryToFile(za, entry, fileno(f));
+        fclose(f);
+
+      done2:
+        free(zip_path);
+        free(dest_path);
+        return strdup(success ? "t" : "");
+    } else {
+        // The one-argument version returns the contents of the file
+        // as the result.
+
+        char* zip_path;
+        char* buffer = NULL;
+
+        if (ReadArgs(state, argv, 1, &zip_path) < 0) return NULL;
+
+        ZipArchive* za = ((UpdaterInfo*)(state->cookie))->package_zip;
+        const ZipEntry* entry = mzFindZipEntry(za, zip_path);
+        if (entry == NULL) {
+            fprintf(stderr, "%s: no %s in package\n", name, zip_path);
+            goto done1;
+        }
+
+        long size = mzGetZipEntryUncompLen(entry);
+        buffer = malloc(size + sizeof(long));
+        if (buffer == NULL) {
+            fprintf(stderr, "%s: failed to allocate %ld bytes for %s\n",
+                    name, size+sizeof(long), zip_path);
+            goto done1;
+        }
+
+        *(long *)buffer = size;
+        success = mzExtractZipEntryToBuffer(
+            za, entry, (unsigned char *)(buffer + sizeof(long)));
+
+      done1:
+        free(zip_path);
+        if (!success) {
+            free(buffer);
+            buffer = malloc(sizeof(long));
+            *(long *)buffer = -1L;
+        }
+        return buffer;
     }
-
-    FILE* f = fopen(dest_path, "wb");
-    if (f == NULL) {
-        fprintf(stderr, "%s: can't open %s for write: %s\n",
-                name, dest_path, strerror(errno));
-        goto done;
-    }
-    success = mzExtractZipEntryToFile(za, entry, fileno(f));
-    fclose(f);
-
-  done:
-    free(zip_path);
-    free(dest_path);
-    return strdup(success ? "t" : "");
 }