You can use runtime checking along with fix and continue to isolate and fix programming errors rapidly. Fix and continue provides a powerful combination that can save you a lot of debugging time. Here is an example:.
% cat -n bug.c 1 #include stdio.h 2 char *s = NULL; 3 4 void 5 problem() 6 { 7 *s = ’c’; 8 } 9 10 main() 11 { 12 problem(); 13 return 0; 14 } % cat -n bug-fixed.c 1 #include stdio.h 2 char *s = NULL; 3 4 void 5 problem() 6 { 7 8 s = (char *)malloc(1); 9 *s = ’c’; 10 } 11 12 main() 13 { 14 problem(); 15 return 0; 16 } yourmachine46: cc -g bug.c yourmachine47: dbx -C a.out Reading symbolic information for a.out Reading symbolic information for rtld /usr/lib/ld.so.1 Reading symbolic information for librtc.so Reading symbolic information for libc.so.1 Reading symbolic information for libintl.so.1 Reading symbolic information for libdl.so.1 Reading symbolic information for libw.so.1 (dbx) check -access access checking - ON (dbx) run Running: a.out (process id 15052) Enabling Error Checking... done Write to unallocated (wua): Attempting to write 1 byte through NULL pointer Current function is problem 7 *s = ’c’; (dbx) pop stopped in main at line 12 in file "bug.c" 12 problem(); (dbx) #at this time we would edit the file; in this example just copy the correct version (dbx) cp bug-fixed.c bug.c (dbx) fix fixing "bug.c" ...... pc moved to "bug.c":14 stopped in main at line 14 in file "bug.c" 14 problem(); (dbx) cont execution completed, exit code is 0 (dbx) quit The following modules in \Qa.out’ have been changed (fixed): bug.c Remember to remake program. |
For more information on using fix and continue, see Memory Leak (mel) Error.