Added conditional compilation for the MD5 hashing.

diff --git a/Makefile b/Makefile
index 7df06bd..fd7146a 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -24,7 +24,13 @@
 BINARY_PATH = /usr/bin
 MAN_PATH = /usr/share/man/man1
 
-LDFLAGS=-lssl
+ifeq ($(WITH_MD5),yes)
+  LDFLAGS=-lssl
+  MD5FLAG=-DWITH_MD5
+else
+  LDFLAGS=
+  MD5FLAG=
+endif
 
 UNAME=\"$(shell uname -srmn)\"
 
@@ -34,7 +40,7 @@ else
   OPTIMIZE_FLAG = -O2
 endif
 
-CFLAGS = -Wall -ansi -pedantic -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -DUNAME="$(UNAME)" $(OPTIMIZE_FLAG)
+CFLAGS = -Wall -ansi -pedantic -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -DUNAME="$(UNAME)" $(MD5FLAG) $(OPTIMIZE_FLAG)
 
 all: finddup
 
@@ -43,12 +49,12 @@ finddup: finddup.o
 
 install: finddup
        install -m 755 finddup $(BINARY_PATH)
-       # install -m 644 finddup.1 $(MAN_PATH)
-       # gzip $(MAN_PATH)/finddup.1
+       install -m 644 finddup.1 $(MAN_PATH)
+       gzip $(MAN_PATH)/finddup.1
 
 uninstall:
        rm $(BINARY_PATH)/finddup
-       # rm $(MAN_PATH)/finddup.1.gz
+       rm $(MAN_PATH)/finddup.1.gz
 
 clean:
        rm -f *.o finddup

diff --git a/finddup.1 b/finddup.1
index 9cc21b4..46a4326 100644 (file)
--- a/finddup.1
+++ b/finddup.1
@@ -69,10 +69,19 @@ use MD5 hashing
 
 None known, probably many. Valgrind does not complain though.
 
-The MD5 hashing often hurts more than it helps, hence it is off by
-default. The only case when it should really be useful is when you
-have plenty of different files of same size, which does not happen
-often.
+The MD5 hashing is not satisfactory. It is computed for a file only if
+the said file has to be read fully for a comparison (i.e. two files
+match and we have to read them completely).
+
+Hence, in practice lot of partial MD5s are computed, which costs a lot
+of cpu and is useless. This often hurts more than it helps, hence it
+is off by default. The only case when it should really be useful is
+when you have plenty of different files of same size, and lot of
+similar ones, which does not happen often.
+
+Forcing the files to be read fully so that the MD5s are properly
+computed is not okay neither, since it would fully read certain files,
+even if we will never need their MD5s.
 
 .SH "WISH LIST"
 

diff --git a/finddup.c b/finddup.c
index ccf21c6..3edfd61 100644 (file)
--- a/finddup.c
+++ b/finddup.c
@@ -40,7 +40,9 @@
 #include <locale.h>
 #include <getopt.h>
 #include <fcntl.h>
+#ifdef WITH_MD5
 #include <openssl/md5.h>
+#endif
 
 /* 1M really helps compared to 64k */
 #define READ_BUFFER_SIZE (1024 * 1024)
@@ -72,7 +74,9 @@ int ignore_same_inode = 0; /* 1 means that comparison between two file
 int tty_width = -1; /* Positive value means what width to use to show
                        the progress bar */
 
+#ifdef WITH_MD5
 int use_md5 = 0; /* 1 means we keep an MD5 signature for each file */
+#endif
 
 /********************************************************************/
 
@@ -105,8 +109,10 @@ struct file_node {
   ino_t inode;
   int group_id; /* one per identical file content */
   int dir_id; /* 1 for DIR1, and 2 for DIR2 */
+#ifdef WITH_MD5
   int md5_computed;
   unsigned char md5[MD5_DIGEST_LENGTH];
+#endif
 };
 
 void file_list_delete(struct file_node *head) {
@@ -133,12 +139,15 @@ int file_list_length(struct file_node *head) {
 int same_content(struct file_node *f1, struct file_node *f2,
                  char *buffer1, char *buffer2) {
   int fd1, fd2, s1, s2;
+
+#ifdef WITH_MD5
   MD5_CTX c1, c2;
 
   if(use_md5) {
-    if(f1->md5_computed && f2->md5_computed &&
-       !memcmp(f1->md5, f2->md5, MD5_DIGEST_LENGTH)) {
-      return 0;
+    if(f1->md5_computed && f2->md5_computed) {
+      if(!memcmp(f1->md5, f2->md5, MD5_DIGEST_LENGTH)) {
+        return 0;
+      }
     } else {
       if(!f1->md5_computed) {
         MD5_Init(&c1);
@@ -148,6 +157,7 @@ int same_content(struct file_node *f1, struct file_node *f2,
       }
     }
   }
+#endif
 
   fd1 = open(f1->name, O_RDONLY);
   fd2 = open(f2->name, O_RDONLY);
@@ -167,6 +177,7 @@ int same_content(struct file_node *f1, struct file_node *f2,
         if(s1 == 0) {
           close(fd1);
           close(fd2);
+#ifdef WITH_MD5
           if(use_md5) {
             if(!f1->md5_computed) {
               MD5_Final(f1->md5, &c1);
@@ -177,8 +188,15 @@ int same_content(struct file_node *f1, struct file_node *f2,
               f2->md5_computed = 1;
             }
           }
+#endif
           return 1;
         } else {
+          if(memcmp(buffer1, buffer2, s1)) {
+            close(fd1);
+            close(fd2);
+            return 0;
+          }
+#ifdef WITH_MD5
           if(use_md5) {
             if(!f1->md5_computed) {
               MD5_Update(&c1, buffer1, s1);
@@ -187,11 +205,7 @@ int same_content(struct file_node *f1, struct file_node *f2,
               MD5_Update(&c2, buffer2, s2);
             }
           }
-          if(memcmp(buffer1, buffer2, s1)) {
-            close(fd1);
-            close(fd2);
-            return 0;
-          }
+#endif
         }
       } else {
         fprintf(stderr,
@@ -266,7 +280,9 @@ struct file_node *scan_directory(struct file_node *tail, const char *name) {
           tmp->inode = sb.st_ino;
           tmp->group_id = -1;
           tmp->dir_id = -1;
+#ifdef WITH_MD5
           tmp->md5_computed = 0;
+#endif
           tail = tmp;
         }
       }
@@ -518,7 +534,9 @@ void print_help(FILE *out) {
   fprintf(out, "   -r, --real-paths           show the real file paths\n");
   fprintf(out, "   -i, --same-inodes-are-different\n");
   fprintf(out, "                              consider files with same inode as different\n");
+#ifdef WITH_MD5
   fprintf(out, "   -m, --md5                  use MD5 hashing\n");
+#endif
   fprintf(out, "\n");
   fprintf(out, "Report bugs and comments to <francois@fleuret.org>.\n");
 }
@@ -582,7 +600,13 @@ int main(int argc, char **argv) {
       break;
 
     case 'm':
+#ifdef WITH_MD5
       use_md5 = 1;
+#else
+      fprintf(stderr,
+              "finddup has not be compiled with MD5 hashing.\n");
+      exit(EXIT_FAILURE);
+#endif
       break;
 
     default: