Fix ggreer#896 - Stream decompress zipped files

Use the POSIX fopencookie(3) mechanism to produce a FILE object, and
then treat them the same as other non-mmapable streams (i.e., FIFOs).

Since some supported platforms do not support fopencookie(3) (Mac OS X,
maybe Cygwin, older BSDs), retain non-streaming zip file support.

Existing tests pass.

Makefile.am

@@ -1,7 +1,7 @@
 ACLOCAL_AMFLAGS = ${ACLOCAL_FLAGS}
 
 bin_PROGRAMS = ag
-ag_SOURCES = src/ignore.c src/ignore.h src/log.c src/log.h src/options.c src/options.h src/print.c src/print_w32.c src/print.h src/scandir.c src/scandir.h src/search.c src/search.h src/lang.c src/lang.h src/util.c src/util.h src/decompress.c src/decompress.h src/uthash.h src/main.c
+ag_SOURCES = src/ignore.c src/ignore.h src/log.c src/log.h src/options.c src/options.h src/print.c src/print_w32.c src/print.h src/scandir.c src/scandir.h src/search.c src/search.h src/lang.c src/lang.h src/util.c src/util.h src/decompress.c src/decompress.h src/uthash.h src/main.c src/zfile.c
 ag_LDADD = ${PCRE_LIBS} ${LZMA_LIBS} ${ZLIB_LIBS} $(PTHREAD_LIBS)
 
 dist_man_MANS = doc/ag.1

configure.ac

@@ -63,7 +63,7 @@ AC_CHECK_DECL([CPU_ZERO, CPU_SET], [AC_DEFINE([USE_CPU_SET], [], [Use CPU_SET ma
 AC_CHECK_MEMBER([struct dirent.d_type], [AC_DEFINE([HAVE_DIRENT_DTYPE], [], [Have dirent struct member d_type])], [], [[#include <dirent.h>]])
 AC_CHECK_MEMBER([struct dirent.d_namlen], [AC_DEFINE([HAVE_DIRENT_DNAMLEN], [], [Have dirent struct member d_namlen])], [], [[#include <dirent.h>]])
 
-AC_CHECK_FUNCS(fgetln getline realpath strlcpy strndup vasprintf madvise posix_fadvise pthread_setaffinity_np pledge)
+AC_CHECK_FUNCS(fgetln fopencookie getline realpath strlcpy strndup vasprintf madvise posix_fadvise pthread_setaffinity_np pledge)
 
 AC_CONFIG_FILES([Makefile the_silver_searcher.spec])
 AC_CONFIG_HEADERS([src/config.h])

src/decompress.h

@@ -1,6 +1,8 @@
 #ifndef DECOMPRESS_H
 #define DECOMPRESS_H
 
+#include <stdio.h>
+
 #include "config.h"
 #include "log.h"
 #include "options.h"
@@ -16,4 +18,9 @@ typedef enum {
 ag_compression_type is_zipped(const void *buf, const int buf_len);
 
 void *decompress(const ag_compression_type zip_type, const void *buf, const int buf_len, const char *dir_full_path, int *new_buf_len);
+
+#if HAVE_FOPENCOOKIE
+FILE *decompress_open(int fd, const char *mode, ag_compression_type ctype);
+#endif
+
 #endif

src/search.c

@@ -357,6 +357,12 @@ void search_file(const char *file_full_path) {
     if (opts.search_zip_files) {
         ag_compression_type zip_type = is_zipped(buf, f_len);
         if (zip_type != AG_NO_COMPRESSION) {
+#if HAVE_FOPENCOOKIE
+            log_debug("%s is a compressed file. stream searching", file_full_path);
+            fp = decompress_open(fd, "r", zip_type);
+            search_stream(fp, file_full_path);
+            fclose(fp);
+#else
             int _buf_len = (int)f_len;
             char *_buf = decompress(zip_type, buf, f_len, file_full_path, &_buf_len);
             if (_buf == NULL || _buf_len == 0) {
@@ -365,6 +371,7 @@ void search_file(const char *file_full_path) {
             }
             search_buf(_buf, _buf_len, file_full_path);
             free(_buf);
+#endif
             goto cleanup;
         }
     }