bsdiff: if file is /dev/fd/*, don't open/close it. Just use the fd.

dev-util/bsdiff/files/4.3_bspatch-support-input-output-positioning.patch

---- work/bsdiff-4.3/bspatch.c   2005-08-16 15:14:00.000000000 -0700
-+++ work/bsdiff-4.3-new/bspatch.c       2010-08-04 10:07:05.000000000 -0700
+--- bsdiff-4.3/bspatch.c        2005-08-16 15:14:00.000000000 -0700
++++ bsdiff-4.3-new/bspatch.c    2010-10-12 13:57:08.000000000 -0700
 @@ -3,7 +3,7 @@
   * All rights reserved
   *
   * Redistribution and use in source and binary forms, with or without
 - * modification, are permitted providing that the following conditions 
 + * modification, are permitted providing that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
-@@ -29,6 +29,9 @@ __FBSDID("$FreeBSD: src/usr.bin/bsdiff/b
+@@ -29,6 +29,9 @@
  #endif
  
  #include <bzlib.h>
 +#include <errno.h>
 +#include <inttypes.h>
 +#include <stdint.h>
  #include <stdlib.h>
  #include <stdio.h>
  #include <string.h>
-@@ -36,6 +39,244 @@ __FBSDID("$FreeBSD: src/usr.bin/bsdiff/b
+@@ -36,6 +39,264 @@
  #include <unistd.h>
  #include <fcntl.h>
  
 +#define JOIN(a, b) __JOIN(a, b)
 +#define __JOIN(a, b) a ## b
 +#define COMPILE_ASSERT(expr, message) \
 +       typedef char JOIN(message, JOIN(_, __LINE__)) [(expr) ? 1 : -1]
 +
 +COMPILE_ASSERT(sizeof(int64_t) == 8, int64_t_64_bit);
 +COMPILE_ASSERT(sizeof(off_t) == 8, off_t_64_bit);
 +
 +#define MIN(a, b) \
 +       ((a) < (b) ? (a) : (b))
 +
++static const char kFdFilePrefix[] = "/dev/fd/";
++
 +// Reads next int from *ints. The int should be terminated with a comma
 +// or NULL char. *ints will be updated to the space right after the comma
 +// or set to NULL if this was the last number. This assumes the input is
 +// a valid string, as validated with PositionsStringIsValid().
 +// Returns 1 on success.
 +int NextInt64(const char** ints, int64_t *out) {
 +       if (!ints[0])
 +               return 0;
 +       int r = sscanf(*ints, "%" PRIi64, out);
 +       if (r == 1) {
@@ skipping 11 matching lines @@
 +       }
 +       return 0;
 +}
 +
 +COMPILE_ASSERT(sizeof(intmax_t) == 8, intmax_t_not_64_bit);
 +
 +// Returns 1 if str can be converted to int64_t without over/underflowing.
 +// str is assumed to point to an optional negative sign followed by numbers,
 +// optionally followed by non-numeric characters, followed by '\0'.
 +int IsValidInt64(const char* str) {
-+       const char* end_ptr = 0;
++       char* end_ptr = 0;
 +       errno = 0;
 +       intmax_t result = strtoimax(str, &end_ptr, /* base: */ 10);
 +       return errno == 0;
 +}
 +
 +// Input validator. Make sure the positions string is well formatted.
 +// All numerical values are checked to make sure they don't over/underflow
 +// int64_t. Returns 1 if valid.
 +int PositionsStringIsValid(const char* positions) {
 +       if (positions == NULL)
@@ skipping 94 matching lines @@
 +       if (length > 0x40000000) {  // 1 GiB; sanity check
 +               errx(1, "Read length too long (exceeds 1 GiB)");
 +       }
 +       // Following bsdiff convention, allocate length + 1 to avoid malloc(0)
 +       char* buf = malloc(length + 1);
 +       if (buf == NULL) {
 +               errx(1, "malloc failed\n");
 +       }
 +       char* buf_tail = buf;
 +
-+       int fd = open(filename, O_RDONLY);
++       int fd = -1;
++       int should_close = 1;
++       if (strlen(filename) > strlen(kFdFilePrefix) &&
++               !strncmp(filename, kFdFilePrefix, strlen(kFdFilePrefix))) {
++               sscanf(filename + strlen(kFdFilePrefix), "%d", &fd);

[petkov, 2010/10/12 21:53:23]

given that you're not detecting errors, why not use atoi?

++               should_close = 0;
++       } else {
++               fd = open(filename, O_RDONLY);
++       }
 +       if (fd < 0) {
 +               errx(1, "open failed for read\n");
 +       }
 +
 +       // Read bytes
 +       p = positions;
 +       for (;;) {
 +               int64_t offset, read_length;
 +               if (NextInt64(&p, &offset) == 0) {
 +                       break;
@@ skipping 11 matching lines @@
 +               }
 +               if (read_length > kMaxLength) {
 +                       errx(1, "read length too large\n");
 +               }
 +               ssize_t rc = pread(fd, buf_tail, (size_t)read_length, (off_t)offset);
 +               if (rc != read_length) {
 +                       errx(1, "read failed\n");
 +               }
 +               buf_tail += rc;
 +       }
-+       close(fd);
++       if (should_close)
++               close(fd);
 +       *old_size = length;
 +       return buf;
 +}
 +
 +static void PositionedWrite(const char* filename,
 +                            const char* positions,
 +                            const char* buf,
 +                            ssize_t new_size) {
 +       if (!PositionsStringIsValid(positions)) {
 +               errx(1, "invalid positions string for write\n");
 +       }
-+       int fd = open(filename, O_WRONLY | O_CREAT, 0666);
++       int fd = -1;
++       int should_close = 1;
++       if (strlen(filename) > strlen(kFdFilePrefix) &&
++               !strncmp(filename, kFdFilePrefix, strlen(kFdFilePrefix))) {
++               sscanf(filename + strlen(kFdFilePrefix), "%d", &fd);
++               should_close = 0;
++       } else {
++               fd = open(filename, O_WRONLY | O_CREAT, 0666);
++       }
 +       if (fd < 0) {
 +               errx(1, "open failed for write\n");
 +       }
 +
 +       for (;;) {
 +               int64_t offset, length;
 +               if (NextInt64(&positions, &offset) == 0) {
 +                       break;
 +               }
 +               if (NextInt64(&positions, &length) == 0) {
@@ skipping 13 matching lines @@
 +                       if (rc != length) {
 +                               errx(1, "write failed\n");
 +                       }
 +               }
 +               buf += length;
 +               new_size -= length;
 +       }
 +       if (new_size != 0) {
 +               errx(1, "output position length doesn't match new size\n");
 +       }
-+       close(fd);
++       if (should_close)
++               close(fd);
 +}
 +
  static off_t offtin(u_char *buf)
  {
         off_t y;
-@@ -69,7 +310,13 @@ int main(int argc,char * argv[])
+@@ -69,7 +330,13 @@
         off_t lenread;
         off_t i;
  
 -       if(argc!=4) errx(1,"usage: %s oldfile newfile patchfile\n",argv[0]);
 +       if ((argc != 6) && (argc != 4)) {
 +               errx(1,"usage: %s oldfile newfile patchfile \\\n"
 +                       "  [in_offset,in_length,in_offset,in_length,... \\\n"
 +                       "  out_offset,out_length,"
 +                       "out_offset,out_length,...]\n",argv[0]);
 +       }
 +       int using_positioning = (argc == 6);
  
         /* Open patch file */
         if ((f = fopen(argv[3], "r")) == NULL)
-@@ -132,12 +379,18 @@ int main(int argc,char * argv[])
+@@ -132,12 +399,18 @@
         if ((epfbz2 = BZ2_bzReadOpen(&ebz2err, epf, 0, 0, NULL, 0)) == NULL)
                 errx(1, "BZ2_bzReadOpen, bz2err = %d", ebz2err);
  
 -       if(((fd=open(argv[1],O_RDONLY,0))<0) ||
 -               ((oldsize=lseek(fd,0,SEEK_END))==-1) ||
 -               ((old=malloc(oldsize+1))==NULL) ||
 -               (lseek(fd,0,SEEK_SET)!=0) ||
 -               (read(fd,old,oldsize)!=oldsize) ||
 -               (close(fd)==-1)) err(1,"%s",argv[1]);
 +       // Read
 +
 +       if (!using_positioning) {
 +               if(((fd=open(argv[1],O_RDONLY,0))<0) ||
 +                       ((oldsize=lseek(fd,0,SEEK_END))==-1) ||
 +                       ((old=malloc(oldsize+1))==NULL) ||
 +                       (lseek(fd,0,SEEK_SET)!=0) ||
 +                       (read(fd,old,oldsize)!=oldsize) ||
 +                       (close(fd)==-1)) err(1,"%s",argv[1]);
 +       } else {
 +               old = PositionedRead(argv[1], argv[4], &oldsize);
 +       }
         if((new=malloc(newsize+1))==NULL) err(1,NULL);
  
         oldpos=0;newpos=0;
-@@ -193,9 +446,13 @@ int main(int argc,char * argv[])
+@@ -193,9 +466,13 @@
                 err(1, "fclose(%s)", argv[3]);
  
         /* Write the new file */
 -       if(((fd=open(argv[2],O_CREAT|O_TRUNC|O_WRONLY,0666))<0) ||
 -               (write(fd,new,newsize)!=newsize) || (close(fd)==-1))
 -               err(1,"%s",argv[2]);
 +       if (!using_positioning) {
 +               if(((fd=open(argv[2],O_CREAT|O_TRUNC|O_WRONLY,0666))<0) ||
 +                       (write(fd,new,newsize)!=newsize) || (close(fd)==-1))
 +                       err(1,"%s",argv[2]);
 +       } else {
 +               PositionedWrite(argv[2], argv[5], new, newsize);
 +       }
  
         free(new);
         free(old);