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Diffstat (limited to 'cmds/idmap/idmap.cpp')
| -rw-r--r-- | cmds/idmap/idmap.cpp | 237 |
1 files changed, 237 insertions, 0 deletions
diff --git a/cmds/idmap/idmap.cpp b/cmds/idmap/idmap.cpp new file mode 100644 index 0000000..46c0edc --- /dev/null +++ b/cmds/idmap/idmap.cpp @@ -0,0 +1,237 @@ +#include "idmap.h" + +#include <private/android_filesystem_config.h> // for AID_SYSTEM + +#include <stdlib.h> +#include <string.h> + +namespace { + const char *usage = "NAME\n\ + idmap - create or display idmap files\n\ +\n\ +SYNOPSIS \n\ + idmap --help \n\ + idmap --fd target overlay fd \n\ + idmap --path target overlay idmap \n\ + idmap --scan dir-to-scan target-to-look-for target dir-to-hold-idmaps \n\ + idmap --inspect idmap \n\ +\n\ +DESCRIPTION \n\ + Idmap files play an integral part in the runtime resource overlay framework. An idmap \n\ + file contains a mapping of resource identifiers between overlay package and its target \n\ + package; this mapping is used during resource lookup. Idmap files also act as control \n\ + files by their existence: if not present, the corresponding overlay package is ignored \n\ + when the resource context is created. \n\ +\n\ + Idmap files are stored in /data/resource-cache. For each pair (target package, overlay \n\ + package), there exists exactly one idmap file, or none if the overlay should not be used. \n\ +\n\ +NOMENCLATURE \n\ + target: the original, non-overlay, package. Each target package may be associated with \n\ + any number of overlay packages. \n\ +\n\ + overlay: an overlay package. Each overlay package is associated with exactly one target \n\ + package, specified in the overlay's manifest using the <overlay target=\"...\"/> \n\ + tag. \n\ +\n\ +OPTIONS \n\ + --help: display this help \n\ +\n\ + --fd: create idmap for target package 'target' (path to apk) and overlay package 'overlay' \n\ + (path to apk); write results to file descriptor 'fd' (integer). This invocation \n\ + version is intended to be used by a parent process with higher privileges to call \n\ + idmap in a controlled way: the parent will open a suitable file descriptor, fork, \n\ + drop its privileges and exec. This tool will continue execution without the extra \n\ + privileges, but still have write access to a file it could not have opened on its \n\ + own. \n\ +\n\ + --path: create idmap for target package 'target' (path to apk) and overlay package \n\ + 'overlay' (path to apk); write results to 'idmap' (path). \n\ +\n\ + --scan: non-recursively search directory 'dir-to-scan' (path) for overlay packages with \n\ + target package 'target-to-look-for' (package name) present at 'target' (path to \n\ + apk). For each overlay package found, create an idmap file in 'dir-to-hold-idmaps' \n\ + (path). \n\ +\n\ + --inspect: decode the binary format of 'idmap' (path) and display the contents in a \n\ + debug-friendly format. \n\ +\n\ +EXAMPLES \n\ + Create an idmap file: \n\ +\n\ + $ adb shell idmap --path /system/app/target.apk \\ \n\ + /vendor/overlay/overlay.apk \\ \n\ + /data/resource-cache/vendor@overlay@overlay.apk@idmap \n\ +\n\ + Display an idmap file: \n\ +\n\ + $ adb shell idmap --inspect /data/resource-cache/vendor@overlay@overlay.apk@idmap \n\ + SECTION ENTRY VALUE OFFSET COMMENT \n\ + IDMAP HEADER magic 0x706d6469 0x0 \n\ + base crc 0x484aa77f 0x1 \n\ + overlay crc 0x03c66fa5 0x2 \n\ + base path .......... 0x03-0x42 /system/app/target.apk \n\ + overlay path .......... 0x43-0x82 /vendor/overlay/overlay.apk \n\ + DATA HEADER types count 0x00000003 0x83 \n\ + padding 0x00000000 0x84 \n\ + type offset 0x00000004 0x85 absolute offset 0x87, xml \n\ + type offset 0x00000007 0x86 absolute offset 0x8a, string \n\ + DATA BLOCK entry count 0x00000001 0x87 \n\ + entry offset 0x00000000 0x88 \n\ + entry 0x7f020000 0x89 xml/integer \n\ + DATA BLOCK entry count 0x00000002 0x8a \n\ + entry offset 0x00000000 0x8b \n\ + entry 0x7f030000 0x8c string/str \n\ + entry 0x7f030001 0x8d string/str2 \n\ +\n\ + In this example, the overlay package provides three alternative resource values:\n\ + xml/integer, string/str and string/str2.\n\ +\n\ +NOTES \n\ + This tool and its expected invocation from installd is modelled on dexopt."; + + bool verify_directory_readable(const char *path) + { + return access(path, R_OK | X_OK) == 0; + } + + bool verify_directory_writable(const char *path) + { + return access(path, W_OK) == 0; + } + + bool verify_file_readable(const char *path) + { + return access(path, R_OK) == 0; + } + + bool verify_root_or_system() + { + uid_t uid = getuid(); + gid_t gid = getgid(); + + return (uid == 0 && gid == 0) || (uid == AID_SYSTEM && gid == AID_SYSTEM); + } + + int maybe_create_fd(const char *target_apk_path, const char *overlay_apk_path, + const char *idmap_str) + { + // anyone (not just root or system) may do --fd -- the file has + // already been opened by someone else on our behalf + + char *endptr; + int idmap_fd = strtol(idmap_str, &endptr, 10); + if (*endptr != '\0') { + fprintf(stderr, "error: failed to parse file descriptor argument %s\n", idmap_str); + return -1; + } + + if (!verify_file_readable(target_apk_path)) { + ALOGD("error: failed to read apk %s: %s\n", target_apk_path, strerror(errno)); + return -1; + } + + if (!verify_file_readable(overlay_apk_path)) { + ALOGD("error: failed to read apk %s: %s\n", overlay_apk_path, strerror(errno)); + return -1; + } + + return idmap_create_fd(target_apk_path, overlay_apk_path, idmap_fd); + } + + int maybe_create_path(const char *target_apk_path, const char *overlay_apk_path, + const char *idmap_path) + { + if (!verify_root_or_system()) { + fprintf(stderr, "error: permission denied: not user root or user system\n"); + return -1; + } + + if (!verify_file_readable(target_apk_path)) { + ALOGD("error: failed to read apk %s: %s\n", target_apk_path, strerror(errno)); + return -1; + } + + if (!verify_file_readable(overlay_apk_path)) { + ALOGD("error: failed to read apk %s: %s\n", overlay_apk_path, strerror(errno)); + return -1; + } + + return idmap_create_path(target_apk_path, overlay_apk_path, idmap_path); + } + + int maybe_scan(const char *overlay_dir, const char *target_package_name, + const char *target_apk_path, const char *idmap_dir) + { + if (!verify_root_or_system()) { + fprintf(stderr, "error: permission denied: not user root or user system\n"); + return -1; + } + + if (!verify_directory_readable(overlay_dir)) { + ALOGD("error: no read access to %s: %s\n", overlay_dir, strerror(errno)); + return -1; + } + + if (!verify_file_readable(target_apk_path)) { + ALOGD("error: failed to read apk %s: %s\n", target_apk_path, strerror(errno)); + return -1; + } + + if (!verify_directory_writable(idmap_dir)) { + ALOGD("error: no write access to %s: %s\n", idmap_dir, strerror(errno)); + return -1; + } + + return idmap_scan(overlay_dir, target_package_name, target_apk_path, idmap_dir); + } + + int maybe_inspect(const char *idmap_path) + { + // anyone (not just root or system) may do --inspect + if (!verify_file_readable(idmap_path)) { + ALOGD("error: failed to read idmap %s: %s\n", idmap_path, strerror(errno)); + return -1; + } + return idmap_inspect(idmap_path); + } +} + +int main(int argc, char **argv) +{ +#if 0 + { + char buf[1024]; + buf[0] = '\0'; + for (int i = 0; i < argc; ++i) { + strncat(buf, argv[i], sizeof(buf) - 1); + strncat(buf, " ", sizeof(buf) - 1); + } + ALOGD("%s:%d: uid=%d gid=%d argv=%s\n", __FILE__, __LINE__, getuid(), getgid(), buf); + } +#endif + + if (argc == 2 && !strcmp(argv[1], "--help")) { + printf("%s\n", usage); + return 0; + } + + if (argc == 5 && !strcmp(argv[1], "--fd")) { + return maybe_create_fd(argv[2], argv[3], argv[4]); + } + + if (argc == 5 && !strcmp(argv[1], "--path")) { + return maybe_create_path(argv[2], argv[3], argv[4]); + } + + if (argc == 6 && !strcmp(argv[1], "--scan")) { + return maybe_scan(argv[2], argv[3], argv[4], argv[5]); + } + + if (argc == 3 && !strcmp(argv[1], "--inspect")) { + return maybe_inspect(argv[2]); + } + + fprintf(stderr, "Usage: don't use this (cf dexopt usage).\n"); + return EXIT_FAILURE; +} |