Fix tar checksum calculation bug.

 -Erik

diff --git a/archival/tar.c b/archival/tar.c
index 49d4d2e..02fde0a 100644 (file)
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -154,10 +154,6 @@ struct TarInfo
 };
 typedef struct TarInfo TarInfo;
 
-/* Static data  */
-static const unsigned long TarChecksumOffset = (const unsigned long)&(((TarHeader *)0)->chksum);
-
-
 /* Local procedures to restore files from a tar file.  */
 static int readTarFile(const char* tarName, int extractFlag, int listFlag, 
                int tostdoutFlag, int verboseFlag, char** excludeList);
@@ -472,10 +468,23 @@ static int
 readTarHeader(struct TarHeader *rawHeader, struct TarInfo *header)
 {
        int i;
-       long chksum, sum;
+       long chksum, sum=0;
        unsigned char *s = (unsigned char *)rawHeader;
 
        header->name  = rawHeader->name;
+       /* Check for and relativify any absolute paths */
+       if ( *(header->name) == '/' ) {
+               static int alreadyWarned=FALSE;
+
+               while (*(header->name) == '/')
+                       ++*(header->name);
+
+               if (alreadyWarned == FALSE) {
+                       errorMsg("tar: Removing leading '/' from member names\n");
+                       alreadyWarned = TRUE;
+               }
+       }
+
        header->mode  = getOctal(rawHeader->mode, sizeof(rawHeader->mode));
        header->uid   =  getOctal(rawHeader->uid, sizeof(rawHeader->uid));
        header->gid   =  getOctal(rawHeader->gid, sizeof(rawHeader->gid));
@@ -484,16 +493,32 @@ readTarHeader(struct TarHeader *rawHeader, struct TarInfo *header)
        chksum = getOctal(rawHeader->chksum, sizeof(rawHeader->chksum));
        header->type  = rawHeader->typeflag;
        header->linkname  = rawHeader->linkname;
+       /* Check for and relativify any absolute paths */
+       if ( *(header->linkname) == '/' ) {
+               static int alreadyWarned=FALSE;
+
+               while (*(header->linkname) == '/')
+                       ++*(header->linkname);
+
+               if (alreadyWarned == FALSE) {
+                       errorMsg("tar: Removing leading '/' from link names\n");
+                       alreadyWarned = TRUE;
+               }
+       }
        header->devmajor  = getOctal(rawHeader->devmajor, sizeof(rawHeader->devmajor));
        header->devminor  = getOctal(rawHeader->devminor, sizeof(rawHeader->devminor));
 
        /* Check the checksum */
-       sum = ' ' * sizeof(rawHeader->chksum);
-       for ( i = TarChecksumOffset; i > 0; i-- )
-               sum += *s++;
-       s += sizeof(rawHeader->chksum);       
-       for ( i = (512 - TarChecksumOffset - sizeof(rawHeader->chksum)); i > 0; i-- )
+       for (i = sizeof(*rawHeader); i-- != 0;) {
                sum += *s++;
+       }
+       /* Remove the effects of the checksum field (replace 
+        * with blanks for the purposes of the checksum) */
+       s = rawHeader->chksum;
+       for (i = sizeof(rawHeader->chksum) ; i-- != 0;) {
+               sum -= *s++;
+       }
+       sum += ' ' * sizeof(rawHeader->chksum);
        if (sum == chksum )
                return ( TRUE);
        return( FALSE);
@@ -511,7 +536,6 @@ static int readTarFile(const char* tarName, int extractFlag, int listFlag,
        int errorFlag=FALSE;
        TarHeader rawHeader;
        TarInfo header;
-       int alreadyWarned=FALSE;
        //int skipFileFlag=FALSE;
 
        /* Open the tar file for reading.  */
@@ -545,18 +569,6 @@ static int readTarFile(const char* tarName, int extractFlag, int listFlag,
                if ( *(header.name) == '\0' )
                                goto endgame;
 
-               /* Check for and relativify any absolute paths */
-               if ( *(header.name) == '/' ) {
-
-                       while (*(header.name) == '/')
-                               ++*(header.name);
-
-                       if (alreadyWarned == FALSE) {
-                               errorMsg("Absolute path detected, removing leading slashes\n");
-                               alreadyWarned = TRUE;
-                       }
-               }
-
                /* Special treatment if the list (-t) flag is on */
                if (verboseFlag == TRUE && extractFlag == FALSE) {
                        int len, len1;
@@ -751,13 +763,14 @@ writeTarHeader(struct TarBallInfo *tbInfo, const char *fileName, struct stat *st
                        errorMsg("tar: Removing leading '/' from member names\n");
                        alreadyWarned=TRUE;
                }
-               strcpy(header.name, fileName+1); 
+               strncpy(header.name, fileName+1, sizeof(header.name)); 
        }
        else {
-               strcpy(header.name, fileName); 
+               strncpy(header.name, fileName, sizeof(header.name)); 
        }
-#if 0
-       /* Now that leading '/''s have been removed */
+
+       /* Now that leading '/''s have been removed, 
+        * check for excluded files....  */
        for (tmpList=tbInfo->excludeList; tmpList && *tmpList; tmpList++) {
                printf( "comparing '%s' and '%s'", *tmpList, header.name);
                if (strcmp( *tmpList, header.name)==0)
@@ -765,7 +778,6 @@ writeTarHeader(struct TarBallInfo *tbInfo, const char *fileName, struct stat *st
                else
                        printf( "\n");
        }
-#endif
 
        putOctal(header.mode, sizeof(header.mode), statbuf->st_mode);
        putOctal(header.uid, sizeof(header.uid), statbuf->st_uid);
@@ -775,15 +787,15 @@ writeTarHeader(struct TarBallInfo *tbInfo, const char *fileName, struct stat *st
        strncpy(header.magic, TAR_MAGIC TAR_VERSION, 
                        TAR_MAGIC_LEN + TAR_VERSION_LEN );
 
+       /* Enter the user and group names (default to root if it fails) */
        my_getpwuid(header.uname, statbuf->st_uid);
-       /* Put some sort of sane fallback in place... */
        if (! *header.uname)
-               strncpy(header.uname, "root", 5);
+               strcpy(header.uname, "root");
        my_getgrgid(header.gname, statbuf->st_gid);
        if (! *header.uname)
-               strncpy(header.uname, "root", 5);
+               strcpy(header.uname, "root");
 
-       // FIXME: (or most likely not) I break Hard Links
+       // FIXME (or most likely not): I break Hard Links
        if (S_ISLNK(statbuf->st_mode)) {
                char buffer[BUFSIZ];
                header.typeflag  = SYMTYPE;
@@ -791,7 +803,17 @@ writeTarHeader(struct TarBallInfo *tbInfo, const char *fileName, struct stat *st
                        errorMsg("Error reading symlink '%s': %s\n", header.name, strerror(errno));
                        return ( FALSE);
                }
-               strncpy(header.linkname, buffer, sizeof(header.linkname)); 
+               if (*buffer=='/') {
+                       static int alreadyWarned=FALSE;
+                       if (alreadyWarned==FALSE) {
+                               errorMsg("tar: Removing leading '/' from link names\n");
+                               alreadyWarned=TRUE;
+                       }
+                       strncpy(header.linkname, buffer+1, sizeof(header.linkname)); 
+               }
+               else {
+                       strncpy(header.linkname, buffer, sizeof(header.linkname)); 
+               }
        } else if (S_ISDIR(statbuf->st_mode)) {
                header.typeflag  = DIRTYPE;
                strncat(header.name, "/", sizeof(header.name)); 

diff --git a/tar.c b/tar.c
index 49d4d2e..02fde0a 100644 (file)
--- a/tar.c
+++ b/tar.c
@@ -154,10 +154,6 @@ struct TarInfo
 };
 typedef struct TarInfo TarInfo;
 
-/* Static data  */
-static const unsigned long TarChecksumOffset = (const unsigned long)&(((TarHeader *)0)->chksum);
-
-
 /* Local procedures to restore files from a tar file.  */
 static int readTarFile(const char* tarName, int extractFlag, int listFlag, 
                int tostdoutFlag, int verboseFlag, char** excludeList);
@@ -472,10 +468,23 @@ static int
 readTarHeader(struct TarHeader *rawHeader, struct TarInfo *header)
 {
        int i;
-       long chksum, sum;
+       long chksum, sum=0;
        unsigned char *s = (unsigned char *)rawHeader;
 
        header->name  = rawHeader->name;
+       /* Check for and relativify any absolute paths */
+       if ( *(header->name) == '/' ) {
+               static int alreadyWarned=FALSE;
+
+               while (*(header->name) == '/')
+                       ++*(header->name);
+
+               if (alreadyWarned == FALSE) {
+                       errorMsg("tar: Removing leading '/' from member names\n");
+                       alreadyWarned = TRUE;
+               }
+       }
+
        header->mode  = getOctal(rawHeader->mode, sizeof(rawHeader->mode));
        header->uid   =  getOctal(rawHeader->uid, sizeof(rawHeader->uid));
        header->gid   =  getOctal(rawHeader->gid, sizeof(rawHeader->gid));
@@ -484,16 +493,32 @@ readTarHeader(struct TarHeader *rawHeader, struct TarInfo *header)
        chksum = getOctal(rawHeader->chksum, sizeof(rawHeader->chksum));
        header->type  = rawHeader->typeflag;
        header->linkname  = rawHeader->linkname;
+       /* Check for and relativify any absolute paths */
+       if ( *(header->linkname) == '/' ) {
+               static int alreadyWarned=FALSE;
+
+               while (*(header->linkname) == '/')
+                       ++*(header->linkname);
+
+               if (alreadyWarned == FALSE) {
+                       errorMsg("tar: Removing leading '/' from link names\n");
+                       alreadyWarned = TRUE;
+               }
+       }
        header->devmajor  = getOctal(rawHeader->devmajor, sizeof(rawHeader->devmajor));
        header->devminor  = getOctal(rawHeader->devminor, sizeof(rawHeader->devminor));
 
        /* Check the checksum */
-       sum = ' ' * sizeof(rawHeader->chksum);
-       for ( i = TarChecksumOffset; i > 0; i-- )
-               sum += *s++;
-       s += sizeof(rawHeader->chksum);       
-       for ( i = (512 - TarChecksumOffset - sizeof(rawHeader->chksum)); i > 0; i-- )
+       for (i = sizeof(*rawHeader); i-- != 0;) {
                sum += *s++;
+       }
+       /* Remove the effects of the checksum field (replace 
+        * with blanks for the purposes of the checksum) */
+       s = rawHeader->chksum;
+       for (i = sizeof(rawHeader->chksum) ; i-- != 0;) {
+               sum -= *s++;
+       }
+       sum += ' ' * sizeof(rawHeader->chksum);
        if (sum == chksum )
                return ( TRUE);
        return( FALSE);
@@ -511,7 +536,6 @@ static int readTarFile(const char* tarName, int extractFlag, int listFlag,
        int errorFlag=FALSE;
        TarHeader rawHeader;
        TarInfo header;
-       int alreadyWarned=FALSE;
        //int skipFileFlag=FALSE;
 
        /* Open the tar file for reading.  */
@@ -545,18 +569,6 @@ static int readTarFile(const char* tarName, int extractFlag, int listFlag,
                if ( *(header.name) == '\0' )
                                goto endgame;
 
-               /* Check for and relativify any absolute paths */
-               if ( *(header.name) == '/' ) {
-
-                       while (*(header.name) == '/')
-                               ++*(header.name);
-
-                       if (alreadyWarned == FALSE) {
-                               errorMsg("Absolute path detected, removing leading slashes\n");
-                               alreadyWarned = TRUE;
-                       }
-               }
-
                /* Special treatment if the list (-t) flag is on */
                if (verboseFlag == TRUE && extractFlag == FALSE) {
                        int len, len1;
@@ -751,13 +763,14 @@ writeTarHeader(struct TarBallInfo *tbInfo, const char *fileName, struct stat *st
                        errorMsg("tar: Removing leading '/' from member names\n");
                        alreadyWarned=TRUE;
                }
-               strcpy(header.name, fileName+1); 
+               strncpy(header.name, fileName+1, sizeof(header.name)); 
        }
        else {
-               strcpy(header.name, fileName); 
+               strncpy(header.name, fileName, sizeof(header.name)); 
        }
-#if 0
-       /* Now that leading '/''s have been removed */
+
+       /* Now that leading '/''s have been removed, 
+        * check for excluded files....  */
        for (tmpList=tbInfo->excludeList; tmpList && *tmpList; tmpList++) {
                printf( "comparing '%s' and '%s'", *tmpList, header.name);
                if (strcmp( *tmpList, header.name)==0)
@@ -765,7 +778,6 @@ writeTarHeader(struct TarBallInfo *tbInfo, const char *fileName, struct stat *st
                else
                        printf( "\n");
        }
-#endif
 
        putOctal(header.mode, sizeof(header.mode), statbuf->st_mode);
        putOctal(header.uid, sizeof(header.uid), statbuf->st_uid);
@@ -775,15 +787,15 @@ writeTarHeader(struct TarBallInfo *tbInfo, const char *fileName, struct stat *st
        strncpy(header.magic, TAR_MAGIC TAR_VERSION, 
                        TAR_MAGIC_LEN + TAR_VERSION_LEN );
 
+       /* Enter the user and group names (default to root if it fails) */
        my_getpwuid(header.uname, statbuf->st_uid);
-       /* Put some sort of sane fallback in place... */
        if (! *header.uname)
-               strncpy(header.uname, "root", 5);
+               strcpy(header.uname, "root");
        my_getgrgid(header.gname, statbuf->st_gid);
        if (! *header.uname)
-               strncpy(header.uname, "root", 5);
+               strcpy(header.uname, "root");
 
-       // FIXME: (or most likely not) I break Hard Links
+       // FIXME (or most likely not): I break Hard Links
        if (S_ISLNK(statbuf->st_mode)) {
                char buffer[BUFSIZ];
                header.typeflag  = SYMTYPE;
@@ -791,7 +803,17 @@ writeTarHeader(struct TarBallInfo *tbInfo, const char *fileName, struct stat *st
                        errorMsg("Error reading symlink '%s': %s\n", header.name, strerror(errno));
                        return ( FALSE);
                }
-               strncpy(header.linkname, buffer, sizeof(header.linkname)); 
+               if (*buffer=='/') {
+                       static int alreadyWarned=FALSE;
+                       if (alreadyWarned==FALSE) {
+                               errorMsg("tar: Removing leading '/' from link names\n");
+                               alreadyWarned=TRUE;
+                       }
+                       strncpy(header.linkname, buffer+1, sizeof(header.linkname)); 
+               }
+               else {
+                       strncpy(header.linkname, buffer, sizeof(header.linkname)); 
+               }
        } else if (S_ISDIR(statbuf->st_mode)) {
                header.typeflag  = DIRTYPE;
                strncat(header.name, "/", sizeof(header.name));