Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: fgets problems
Top Forums Programming fgets problems Post 302397063 by CRGreathouse on Saturday 20th of February 2010 04:33:59 PM
Old 02-20-2010
Quote:
Originally Posted by Corona688
Of all the faith-based initiatives Bush funded, faith-based software maintenance has to be the worst. Smilie Bottom line is, you don't know why it crashed, don't know why it stopped crashing, and don't know if the problem is truly solved yet or not. All we know is that something trashed some memory somewhere somehow. Time for a memory debugger.
I'm just saying that in these functions, the only memory I manage myself is in a single array, char line[]. All other memory management is done by the library. And since library-related memory troubles will be problems *within* the Pari stack rather than overflowing the Pari stack*, the particular tool recommended here seem powerless to help me.

What I would need is something that could help me debug memory use within the Pari stack.

* I recognize that you haven't seen the library code, so this you're going to have to trust... or not.

Quote:
Originally Posted by Corona688
All this odd stack rearranging makes me more and more suspicious of memory trashing, not less!
Agreed. It's error-prone, to be sure. The biggest problem (in my experience with this library) is leaving garbage behind, but I have had occasional problems of corrupted data -- say, moving the pointer too far so that some members of a live structure can be overwritten later.

Quote:
Originally Posted by Corona688
When it works perfectly it works perfectly, but one mistake and you're mangling your own stack frame. It could also be a disguised array-bounds problem, these macros are using hidden stack variables and writing beyond them could smash your stack too.
The testing behind the library code is quite solid; I'm not concerned about it going past the end of the stack or overwriting things in the 'valid data' portion. My code, on the other hand, is comparatively suspect: I could move the pointer to the wrong place, so that the (correct) library code would overwrite my data.

There are, as you suggest, several stack variables, but the only one that I use regularly is avma, the "available memory area" pointer.
 

10 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

'make' problems (compliation problems?)

I'm trying to compile and install both most recent version of 'make' and the most recent version of 'openssh' on my Sparc20. I've run into the following problems... and I don't know what they mean. Can someone please help me resolve these issues? I'm using the 'make' version that was... (5 Replies)
Discussion started by: xyyz
5 Replies

2. UNIX for Dummies Questions & Answers

Problems with ld.so.1

I renamed ld.so.1 on a Sun machine running Solaris 2.6. Now I cannot boot the system and I can use only very few commands in Maintenance Mode. Can someone help me? (3 Replies)
Discussion started by: ciccio
3 Replies

3. Programming

fgets()

does anyone knows how to accept a command from a user.. i was wondering to use fgets(), but got no idea how to start it... (4 Replies)
Discussion started by: skanky
4 Replies

4. Programming

Problem with fgets and rewind function ..

Hello Friends, I got stuck with fgets () & rewind() function .. Please need help.. Actually I am doing a like, The function should read lines from a txt file until the function is called.. If the data from the txt file ends then it goes to the top and then again when the function is called... (1 Reply)
Discussion started by: user_prady
1 Replies

5. Programming

Question about NULL Character & fgets()

Assume client send the message " Hello ", i get output such as Sent mesg: hello Bytes Sent to Client: 6 bytes_received = recv(clientSockD, data, MAX_DATA, 0); if(bytes_received) { send(clientSockD, data, bytes_received, 0); data = '\0';... (2 Replies)
Discussion started by: f.ben.isaac
2 Replies

6. Programming

[C] fgets problem with SIGINT singlal!!!

Hi all, I have this method to read a string from a STDIN: void readLine(char* inputBuffer){ fgets (inputBuffer, MAX_LINE, stdin); fflush(stdin); /* remove '\n' char from string */ if(strlen(inputBuffer) != 0) inputBuffer = '\0'; } All work fine but if i... (1 Reply)
Discussion started by: hurricane86
1 Replies

7. UNIX for Dummies Questions & Answers

Problems with using less

Hello, I am having problems with using less on Linux version 2.6.18-92.1.17.el5 (brewbuilder@hs20-bc1-7.build.redhat.com) (gcc version 4.1.2 20071124 (Red Hat 4.1.2-42)). I am using csh but have the same problems on bash. If I pipe something to less it works perfectly i.e. cat file | less... (9 Replies)
Discussion started by: z1dane
9 Replies

8. Programming

fgets problems newline

hello, i'm trying to write a C-program that reads a file line by line. (and searches each line for a given string) This file is an special ASCII-database-file, with a lot of entries. I checked the line with most length, and it was about 4000 characters. With google i found several... (4 Replies)
Discussion started by: p1cm1n
4 Replies

9. Programming

fgets read file line with "\n" inside

Hi, I have a string like this, char str ="This, a sample string.\\nThis is the second line, \\n \\n, we will have one blank line"; if I want to use strtok() to seperate the string, which token should I use? I tried "\n", "\\n", either not working. peter (1 Reply)
Discussion started by: laopi
1 Replies

10. Shell Programming and Scripting

while and do problems

Any ideas how to clear this error as it seems I dont understand if,do,while and els commands #!/bin/ksh set -x print "This script creates test messages" print "Please enter test case name" read testcasename echo $testcasename skipfield=Y while print "Do you want to skip this field... (4 Replies)
Discussion started by: andrew.p.mcderm
4 Replies

LEARN ABOUT HPUX

u_stack_trace

U_STACK_TRACE(3X)														 U_STACK_TRACE(3X)

NAME

       U_STACK_TRACE(), _UNW_STACK_TRACE() - produce a trace back of the procedure call stack using the unwind library

SYNOPSIS

DESCRIPTION

       prints  a  formatted stack trace to standard error.  produces a formatted stack trace on the output stream indicated by parameter out_file.
       The stream must be a writable stream for output to be produced.

APPLICATION USAGE

       and are thread-safe.  They are not async-cancel-safe because they make use of which is not async-cancel-safe.   A  cancellation	point  may
       occur when a thread is executing

RETURN VALUE

       None

ERRORS

       can fail to give the entire stack back trace under the following conditions:

       o  Low memory conditions.  The unwind library is not able to allocate enough memory to perform the tasks of tracking back over the stack or
	  of looking up symbols names associated with instruction pointer addresses encountered.

       o  Executables and shared libraries that fail to conform to the Runtime Architecture for Itanium-based systems.	For example, they may have
	  invalid, incomplete, or missing unwind tables; or invalid or incorrect unwind information blocks.

EXAMPLES

       Given the following C program:

       Compiling and executing the program produces output similar to this:

AUTHOR

       was developed by HP.

SEE ALSO

       _UNW_createContextForSelf(3X), _UNW_currentContext(3X), _UNW_getGR(3X), unwind(5).

							   Itanium(R)-based System Only 					 U_STACK_TRACE(3X)
All times are GMT -4. The time now is 04:34 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy