Question

see i am just using valgrind for detecting memory leakage in my code. so i have used

valgrind -v --leak-check=full --show-reachable=yes  ./my_binary

i see following out which i can not understand

`==16545== 
==16545== HEAP SUMMARY:
==16545==     in use at exit: 20,171 bytes in 647 blocks
==16545==   total heap usage: 993 allocs, 346 frees, 30,090 bytes allocated
==16545== 
==16545== Searching for pointers to 647 not-freed blocks
==16545== Checked 124,548 bytes
==16545== 
==16545== 1 bytes in 1 blocks are still reachable in loss record 1 of 253
==16545==    at 0x400677E: malloc (vg_replace_malloc.c:195)
==16545==    by 0x80AAB31: xmalloc (in /bin/bash)
==16545==    by 0x80796D0: make_variable_value (in /bin/bash)
==16545==    by 0x80798C8: ??? (in /bin/bash)
==16545==    by 0x807BA40: initialize_shell_variables (in /bin/bash)
==16545==    by 0x805E897: ??? (in /bin/bash)
==16545==    by 0x805FA10: main (in /bin/bash)
==16545== 
==16545== 1 bytes in 1 blocks are still reachable in loss record 2 of 253
==16545==    at 0x400677E: malloc (vg_replace_malloc.c:195)
==16545==    by 0x80AAB31: xmalloc (in /bin/bash)
==16545==    by 0x80A578B: set_locale_var (in /bin/bash)
==16545==    by 0x80A5912: set_default_lang (in /bin/bash)
==16545==    by 0x805FA15: main (in /bin/bash)
==16545== 
==16545== 1 bytes in 1 blocks are still reachable in loss record 3 of 253
==16545==    at 0x400677E: malloc (vg_replace_malloc.c:195)
==16545==    by 0x80AAB31: xmalloc (in /bin/bash)
==16545==    by 0x8061B9B: ??? (in /bin/bash)
==16545==    by 0x8062D95: ??? (in /bin/bash)
==16545==    by 0x8065481: ??? (in /bin/bash)
==16545==    by 0x806801A: yyparse (in /bin/bash)
==16545==    by 0x8060580: parse_command (in /bin/bash)
==16545==    by 0x806064F: read_command (in /bin/bash)
==16545==    by 0x80608AE: reader_loop (in /bin/bash)
==16545==    by 0x805FEFB: main (in /bin/bash)`e

i just want to understand this.?
why this does not giving me particular line no in ma code which has not freed ?

Answer 1

These errors come from /bin/bash not from your own code. Are you running any bash scripts from your code? Here is explanation of what it means. I think you can just ignore it.

“still reachable” means your program is probably ok — it didn’t free
some memory it could have. This is quite common and often reasonable.
Don’t use –show-reachable=yes if you don’t want to see these reports.