Hi,
As Christian said, probably your heap is corrupted. Your backtrace
clearly indicates that.
The typical errors that lead to this are
- you free() some memory twice
- you free more or less memory than you malloc() ed
- you overrun a buffer on the heap
valgrind is a good tool to detect such mistakes.
Martin
[EMAIL PROTECTED] schrieb:
tanx for the advice...but how to avoid heap corruption? and why does it happen?
anyway, finally here is the backtrace:
*** glibc detected *** malloc(): memory corruption: 0x0808e078 ***
Program received signal SIGABRT, Aborted.
[Switching to Thread -1213548864 (LWP 4348)]
0xffffe410 in __kernel_vsyscall ()
(gdb) ba
#0 0xffffe410 in __kernel_vsyscall ()
#1 0x4fad57d5 in raise () from /lib/tls/libc.so.6
#2 0x4fad7149 in abort () from /lib/tls/libc.so.6
#3 0x4fb0927a in __libc_message () from /lib/tls/libc.so.6
#4 0x4fb1049c in _int_malloc () from /lib/tls/libc.so.6
#5 0x4fb11f01 in malloc () from /lib/tls/libc.so.6
#6 0xb7d95c03 in sqlite3Malloc (n=-16) at ./src/util.c:296
#7 0xb7d885f2 in sqlite3ParserAlloc (
mallocProc=0xb7d95bdc <sqlite3Malloc>) at parse.c:1302
#8 0xb7d9382d in sqlite3RunParser (pParse=0xbffff550,
zSql=0x8093c38 "SELECT subjNum FROM \"images\" WHERE id==15;",
pzErrMsg=0xbffff54c) at ./src/tokenize.c:349
#9 0xb7d8c777 in sqlite3_prepare (db=0x808d5d0,
zSql=0x8093c38 "SELECT subjNum FROM \"images\" WHERE id==15;",
nBytes=-1, ppStmt=0xbffff648, pzTail=0x0) at ./src/prepare.c:440
#10 0x0804d0ef in subjId (db=0x808d5d0, id=15, subj=0xbffff748,
test=0x0) at database.c:901
#11 0x0804e8f8 in featVect (db=0x808d5d0, recog_id=1, maxEigen=0)
at database.c:1662
#12 0x0804a26a in main (argc=5, argv=0xbffff864) at main.c:400
(gdb)
I also noticed that error occours even if the requested row id is every time
the same!
So the problem occours after a certain number of iterations.
The code to read is something like this:
sqlite3_stmt *pStmt=0;
char *sql=0;
int sql_error=0;
asprintf(&sql, "SELECT subjNum FROM \"images\" WHERE id==%d;" id);
if ( !sqlite3_prepare(db, sql, -1, &pStmt, 0) )
{
if (sqlite3_step(pStmt)==SQLITE_ROW)
{
test = (char*) sqlite3_column_text (pStmt,0);
}
else
{
fprintf(stderr,"\nWARNING: No image associated to requested
id\n");
sql_error = 1;
}
}
else
{
fprintf(stderr, "\nERROR: SQL prepare error:\n\t%s\n",
sqlite3_errmsg(db));
sql_error=1;
}
if ( sqlite3_finalize(pStmt) != SQLITE_OK )
{
fprintf(stderr, "\nERROR: SQL finalization error:\n\t%s\n",
sqlite3_errmsg(db));
sql_error=1;
}
free(sql);
if (sql_error)
{
sqlite3_close (db);
exit(1);
}
it is inside a function that is called iteratively from another function,
incrementing the passed id num
tanks
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