sed: correctly handle 'w FILE' commands writing to the same file

function                                             old     new   delta
sed_xfopen_w                                           -      84     +84

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

2 files changed, 38 insertions, 2 deletions

diff --git a/editors/sed.c b/editors/sed.c
index e8c82ac63..48b0dbf67 100644
--- a/editors/sed.c
+++ b/editors/sed.c
@@ -97,6 +97,12 @@ enum {
         OPT_in_place = 1 << 0,
 };
 
+struct sed_FILE {
+        struct sed_FILE *next; /* Next (linked list, NULL terminated) */
+        const char *fname;
+        FILE *fp;
+};
+
 /* Each sed command turns into one of these structures. */
 typedef struct sed_cmd_s {
         /* Ordered by alignment requirements: currently 36 bytes on x86 */
@@ -151,6 +157,11 @@ struct globals {
         /* linked list of append lines */
         llist_t *append_head;
 
+        /* linked list of FILEs opened for 'w' and s///w'.
+         * Needed to handle duplicate fnames: sed '/a/w F;/b/w F'
+         */
+        struct sed_FILE *FILE_head;
+
         char *add_cmd_line;
 
         struct pipeline {
@@ -211,6 +222,22 @@ static void sed_free_and_close_stuff(void)
 void sed_free_and_close_stuff(void);
 #endif
 
+static FILE *sed_xfopen_w(const char *fname)
+{
+        struct sed_FILE **pp = &G.FILE_head;
+        struct sed_FILE *cur;
+        while ((cur = *pp) != NULL) {
+                if (strcmp(cur->fname, fname) == 0)
+                        return cur->fp;
+                pp = &cur->next;
+        }
+        *pp = cur = xzalloc(sizeof(*cur));
+        /*cur->next = NULL; - already is */
+        cur->fname = xstrdup(fname);
+        cur->fp = xfopen_for_write(fname);
+        return cur->fp;
+}
+
 /* If something bad happens during -i operation, delete temp file */
 
 static void cleanup_outname(void)
@@ -446,7 +473,7 @@ static int parse_subst_cmd(sed_cmd_t *sed_cmd, const char *substr)
                 {
                         char *fname;
                         idx += parse_file_cmd(/*sed_cmd,*/ substr+idx+1, &fname);
-                        sed_cmd->sw_file = xfopen_for_write(fname);
+                        sed_cmd->sw_file = sed_xfopen_w(fname);
                         sed_cmd->sw_last_char = '\n';
                         free(fname);
                         break;
@@ -561,7 +588,7 @@ static const char *parse_cmd_args(sed_cmd_t *sed_cmd, const char *cmdstr)
                 }
                 cmdstr += parse_file_cmd(/*sed_cmd,*/ cmdstr, &sed_cmd->string);
                 if (sed_cmd->cmd == 'w') {
-                        sed_cmd->sw_file = xfopen_for_write(sed_cmd->string);
+                        sed_cmd->sw_file = sed_xfopen_w(sed_cmd->string);
                         sed_cmd->sw_last_char = '\n';
                 }
         }
diff --git a/testsuite/sed.tests b/testsuite/sed.tests
index 2b78c9b12..e62b839f7 100755
--- a/testsuite/sed.tests
+++ b/testsuite/sed.tests
@@ -405,6 +405,15 @@ testing "sed ^ OR not^" \
         "" \
         "abca\n"
 
+# This only works if file name is exactly the same.
+# For example, w FILE; w ./FILE won't work.
+testing "sed understands duplicate file name" \
+        "sed -n -e '/a/w sed.output' -e '/c/w sed.output' 2>&1 && cat sed.output && rm sed.output" \
+        "a\nc\n" \
+        "" \
+        "a\nb\nc\n"
+
+
 # testing "description" "commands" "result" "infile" "stdin"
 
 exit $FAILCOUNT