sim: igen: support in-place updates ourself

Every file that igen outputs is then processed with the move-if-changed
shell script.  This creates a lot of boilerplate in the build and not an
insignificant amount of build-time overhead.  Move the simple "is the file
changed" logic into igen itself.

diff --git a/sim/igen/lf.c b/sim/igen/lf.c
index ca7a56ab0aa33fdaf184914f29532aa3ed5664eb..9316dd6d15880f7a7e6a6192ad3ed740f68ba9dd 100644 (file)
--- a/sim/igen/lf.c
+++ b/sim/igen/lf.c
@@ -20,7 +20,7 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 
-
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdarg.h>
 #include <ctype.h>
@@ -37,7 +37,9 @@ struct _lf
   int line_nr;                 /* nr complete lines written, curr line is line_nr+1 */
   int indent;
   int line_blank;
-  const char *name;
+  const char *name;            /* Output name with diagnostics.  */
+  const char *filename;                /* Output filename.  */
+  char *tmpname;               /* Temporary output filename.  */
   const char *program;
   lf_file_references references;
   lf_file_type type;
@@ -56,6 +58,7 @@ lf_open (const char *name,
   new_lf->references = references;
   new_lf->type = type;
   new_lf->name = (real_name == NULL ? name : real_name);
+  new_lf->filename = name;
   new_lf->program = program;
   /* attach to stdout if pipe */
   if (!strcmp (name, "-"))
@@ -65,7 +68,11 @@ lf_open (const char *name,
   else
     {
       /* create a new file */
-      new_lf->stream = fopen (name, "w");
+      char *tmpname = zalloc (strlen (name) + 5);
+      sprintf (tmpname, "%s.tmp", name);
+      new_lf->filename = name;
+      new_lf->tmpname = tmpname;
+      new_lf->stream = fopen (tmpname, "w+");
       if (new_lf->stream == NULL)
        {
          perror (name);
@@ -86,15 +93,73 @@ lf_get_file_type (const lf *file)
 void
 lf_close (lf *file)
 {
-  if (file->stream != stdout)
+  FILE *fp;
+  bool update = true;
+
+  /* If we wrote to stdout, no house keeping needed.  */
+  if (file->stream == stdout)
+    return;
+
+  /* Rename the temp file to the real file if it's changed.  */
+  fp = fopen (file->filename, "r");
+  if (fp != NULL)
     {
-      if (fclose (file->stream))
+      off_t len;
+
+      fseek (fp, 0, SEEK_END);
+      len = ftell (fp);
+
+      if (len == ftell (file->stream))
        {
-         perror ("lf_close.fclose");
+         off_t off;
+         size_t cnt;
+         char *oldbuf = zalloc (len);
+         char *newbuf = zalloc (len);
+
+         rewind (fp);
+         off = 0;
+         while ((cnt = fread (oldbuf + off, 1, len - off, fp)) > 0)
+           off += cnt;
+         ASSERT (off == len);
+
+         rewind (file->stream);
+         off = 0;
+         while ((cnt = fread (newbuf + off, 1, len - off, file->stream)) > 0)
+           off += cnt;
+         ASSERT (off == len);
+
+         if (memcmp (oldbuf, newbuf, len) == 0)
+           update = false;
+       }
+
+      fclose (fp);
+    }
+
+  if (fclose (file->stream))
+    {
+      perror ("lf_close.fclose");
+      exit (1);
+    }
+
+  if (update)
+    {
+      if (rename (file->tmpname, file->filename) != 0)
+       {
+         perror ("lf_close.rename");
+         exit (1);
+       }
+    }
+  else
+    {
+      if (remove (file->tmpname) != 0)
+       {
+         perror ("lf_close.unlink");
          exit (1);
        }
-      free (file);
     }
+
+  free (file->tmpname);
+  free (file);
 }
 
 

diff --git a/sim/ppc/lf.c b/sim/ppc/lf.c
index c40de5b5c5dbaa72d3ba29d79c3f8eb0096f0e12..e170a47b0902f2897d8ff5a74f2d0893b6302039 100644 (file)
--- a/sim/ppc/lf.c
+++ b/sim/ppc/lf.c
@@ -17,7 +17,7 @@
 
     */
 
-
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdarg.h>
 #include <ctype.h>
@@ -34,7 +34,9 @@ struct _lf {
   int line_nr; /* nr complete lines written, curr line is line_nr+1 */
   int indent;
   int line_blank;
-  const char *name;
+  const char *name;            /* Output name with diagnostics.  */
+  const char *filename;                /* Output filename.  */
+  char *tmpname;               /* Temporary output filename.  */
   const char *program;
   lf_file_references references;
   lf_file_type type;
@@ -54,6 +56,7 @@ lf_open(const char *name,
   new_lf->references = references;
   new_lf->type = type;
   new_lf->name = (real_name == NULL ? name : real_name);
+  new_lf->filename = name;
   new_lf->program = program;
   /* attach to stdout if pipe */
   if (!strcmp(name, "-")) {
@@ -61,7 +64,11 @@ lf_open(const char *name,
   }
   else {
     /* create a new file */
-    new_lf->stream = fopen(name, "w");
+    char *tmpname = zalloc (strlen (name) + 5);
+    sprintf (tmpname, "%s.tmp", name);
+    new_lf->filename = name;
+    new_lf->tmpname = tmpname;
+    new_lf->stream = fopen(tmpname, "w+");
     if (new_lf->stream == NULL) {
       perror(name);
       exit(1);
@@ -74,13 +81,73 @@ lf_open(const char *name,
 void
 lf_close(lf *file)
 {
-  if (file->stream != stdout) {
-    if (fclose(file->stream)) {
-      perror("lf_close.fclose");
-      exit(1);
+  FILE *fp;
+  bool update = true;
+
+  /* If we wrote to stdout, no house keeping needed.  */
+  if (file->stream == stdout)
+    return;
+
+  /* Rename the temp file to the real file if it's changed.  */
+  fp = fopen (file->filename, "r");
+  if (fp != NULL)
+    {
+      off_t len;
+
+      fseek (fp, 0, SEEK_END);
+      len = ftell (fp);
+
+      if (len == ftell (file->stream))
+       {
+         off_t off;
+         size_t cnt;
+         char *oldbuf = zalloc (len);
+         char *newbuf = zalloc (len);
+
+         rewind (fp);
+         off = 0;
+         while ((cnt = fread (oldbuf + off, 1, len - off, fp)) > 0)
+           off += cnt;
+         ASSERT (off == len);
+
+         rewind (file->stream);
+         off = 0;
+         while ((cnt = fread (newbuf + off, 1, len - off, file->stream)) > 0)
+           off += cnt;
+         ASSERT (off == len);
+
+         if (memcmp (oldbuf, newbuf, len) == 0)
+           update = false;
+       }
+
+      fclose (fp);
     }
-    free(file);
-  }
+
+  if (fclose (file->stream))
+    {
+      perror ("lf_close.fclose");
+      exit (1);
+    }
+
+  if (update)
+    {
+      if (rename (file->tmpname, file->filename) != 0)
+       {
+         perror ("lf_close.rename");
+         exit (1);
+       }
+    }
+  else
+    {
+      if (remove (file->tmpname) != 0)
+       {
+         perror ("lf_close.unlink");
+         exit (1);
+       }
+    }
+
+  free (file->tmpname);
+  free (file);
 }