sed: open input files sequentially to avoid EMFILE

Currently, sed pre-opens all files, which may cause EMFILE errors
on systems with low ulimit -n.  Change sed to open one file at a time.

function                                             old     new   delta
get_next_line                                        177     235     +58
sed_main                                             682     652     -30
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 58/-30)             Total: 28 bytes

Based on the patch by Daniel Borca <dborca@yahoo.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 36 insertions, 27 deletions

diff --git a/editors/sed.c b/editors/sed.c
index 777f38308..87fa00291 100644
--- a/editors/sed.c
+++ b/editors/sed.c
@@ -23,7 +23,7 @@
  * resulting sed_cmd_t structures are appended to a linked list
  * (G.sed_cmd_head/G.sed_cmd_tail).
  *
- * add_input_file() adds a FILE* to the list of input files.  We need to
+ * add_input_file() adds a char* to the list of input files.  We need to
  * know all input sources ahead of time to find the last line for the $ match.
  *
  * process_files() does actual sedding, reading data lines from each input FILE*
@@ -135,12 +135,15 @@ static const char semicolon_whitespace[] ALIGN1 = "; \n\r\t\v";
 struct globals {
         /* options */
         int be_quiet, regex_type;
+
         FILE *nonstdout;
         char *outname, *hold_space;
+        smallint exitcode;
 
-        /* List of input files */
+        /* list of input files */
         int input_file_count, current_input_file;
-        FILE **input_file_list;
+        const char **input_file_list;
+        FILE *current_fp;
 
         regmatch_t regmatch[10];
         regex_t *previous_regex_ptr;
@@ -148,7 +151,7 @@ struct globals {
         /* linked list of sed commands */
         sed_cmd_t *sed_cmd_head, **sed_cmd_tail;
 
-        /* Linked list of append lines */
+        /* linked list of append lines */
         llist_t *append_head;
 
         char *add_cmd_line;
@@ -200,8 +203,8 @@ static void sed_free_and_close_stuff(void)
 
         free(G.hold_space);
 
-        while (G.current_input_file < G.input_file_count)
-                fclose(G.input_file_list[G.current_input_file++]);
+        if (G.current_fp)
+                fclose(G.current_fp);
 }
 #else
 void sed_free_and_close_stuff(void);
@@ -939,8 +942,20 @@ static char *get_next_line(char *gets_char, char *last_puts_char, char last_gets
         /* will be returned if last line in the file
          * doesn't end with either '\n' or '\0' */
         gc = NO_EOL_CHAR;
-        while (G.current_input_file < G.input_file_count) {
-                FILE *fp = G.input_file_list[G.current_input_file];
+        for (; G.input_file_list[G.current_input_file]; G.current_input_file++) {
+                FILE *fp = G.current_fp;
+                if (!fp) {
+                        const char *path = G.input_file_list[G.current_input_file];
+                        fp = stdin;
+                        if (path != bb_msg_standard_input) {
+                                fp = fopen_or_warn(path, "r");
+                                if (!fp) {
+                                        G.exitcode = EXIT_FAILURE;
+                                        continue;
+                                }
+                        }
+                        G.current_fp = fp;
+                }
                 /* Read line up to a newline or NUL byte, inclusive,
                  * return malloc'ed char[]. length of the chunk read
                  * is stored in len. NULL if EOF/error */
@@ -971,8 +986,8 @@ static char *get_next_line(char *gets_char, char *last_puts_char, char last_gets
                  * (note: *no* newline after "b bang"!) */
                 }
                 /* Close this file and advance to next one */
-                fclose(fp);
-                G.current_input_file++;
+                fclose_if_not_stdin(fp);
+                G.current_fp = NULL;
         }
         *gets_char = gc;
         return temp;
@@ -1399,7 +1414,7 @@ static void add_cmd_block(char *cmdstr)
         free(sv);
 }
 
-static void add_input_file(FILE *file)
+static void add_input_file(const char *file)
 {
         G.input_file_list = xrealloc_vector(G.input_file_list, 2, G.input_file_count);
         G.input_file_list[G.input_file_count++] = file;
@@ -1423,8 +1438,6 @@ int sed_main(int argc UNUSED_PARAM, char **argv)
                 "file\0"            Required_argument   "f";
 #endif
 
-        int status = EXIT_SUCCESS;
-
         INIT_G();
 
         /* destroy command strings on exit */
@@ -1491,27 +1504,21 @@ int sed_main(int argc UNUSED_PARAM, char **argv)
         if (argv[0] == NULL) {
                 if (opt & OPT_in_place)
                         bb_error_msg_and_die(bb_msg_requires_arg, "-i");
-                add_input_file(stdin);
+                add_input_file(bb_msg_standard_input);
         } else {
                 int i;
 
                 for (i = 0; argv[i]; i++) {
                         struct stat statbuf;
                         int nonstdoutfd;
-                        FILE *file;
                         sed_cmd_t *sed_cmd;
 
                         if (LONE_DASH(argv[i]) && !(opt & OPT_in_place)) {
-                                add_input_file(stdin);
+                                add_input_file(bb_msg_standard_input);
                                 process_files();
                                 continue;
                         }
-                        file = fopen_or_warn(argv[i], "r");
-                        if (!file) {
-                                status = EXIT_FAILURE;
-                                continue;
-                        }
-                        add_input_file(file);
+                        add_input_file(argv[i]);
                         if (!(opt & OPT_in_place)) {
                                 continue;
                         }
@@ -1523,7 +1530,7 @@ int sed_main(int argc UNUSED_PARAM, char **argv)
                         G.nonstdout = xfdopen_for_write(nonstdoutfd);
 
                         /* Set permissions/owner of output file */
-                        fstat(fileno(file), &statbuf);
+                        stat(argv[i], &statbuf);
                         /* chmod'ing AFTER chown would preserve suid/sgid bits,
                          * but GNU sed 4.2.1 does not preserve them either */
                         fchmod(nonstdoutfd, statbuf.st_mode);
@@ -1549,12 +1556,13 @@ int sed_main(int argc UNUSED_PARAM, char **argv)
                         }
                 }
                 /* Here, to handle "sed 'cmds' nonexistent_file" case we did:
-                 * if (G.current_input_file >= G.input_file_count)
-                 *      return status;
+                 * if (G.current_input_file[G.current_input_file] == NULL)
+                 *      return G.exitcode;
                  * but it's not needed since process_files() works correctly
                  * in this case too. */
         }
+
         process_files();
 
-        return status;
+        return G.exitcode;
 }
diff --git a/libbb/fclose_nonstdin.c b/libbb/fclose_nonstdin.c
index 5ce9d5b48..1b1441347 100644
--- a/libbb/fclose_nonstdin.c
+++ b/libbb/fclose_nonstdin.c
@@ -18,7 +18,8 @@ int FAST_FUNC fclose_if_not_stdin(FILE *f)
 {
         /* Some more paranoid applets want ferror() check too */
         int r = ferror(f); /* NB: does NOT set errno! */
-        if (r) errno = EIO; /* so we'll help it */
+        if (r)
+                errno = EIO; /* so we'll help it */
         if (f != stdin)
                 return (r | fclose(f)); /* fclose does set errno on error */
         return r;