BD-shell 1.0.0 released
Sunday, September 14th, 2008I'm very pleased to announce the final release of my tiny C Unix Shell. Every requirement has been satisfied. I hope I will find the time to expand it
http://bd-things.net/projects/bd-shell/
Posts Tagged ‘C language’
BD-shell 1.0.0 RC2 is out! Processes in background are dangerous
Saturday, September 13th, 2008Release Candidate 2 for my C shell is out. This is a real release candidate, code is frozen and hopefully this one does not have serious bugs like RC1. As you may know, RC1 has been retired because of a bug causing a segmentation fault when launching short commands in background. Let's see why this happened. The following schema summarizes what happens when a program in background is launched:
Schema for BD-shell, anatomy of process handling
As you see, there is a non-synchronous function that is called when the child exits, the SIGCHLD handler.
What if the background command is very short, like ls? It may happen that SIGCHLD is thrown before the job object creation. Bdsh RC1 did not manage this case, and crashed. RC2 fixes this and does not have relevant bugs according to my definition of 1.0.0 release.
Finally, go and grab the code!
BD-shell 1.0.0 RC1 is out!
Friday, September 12th, 2008UPDATE: due to a very serious bug, the rc1 has been retired and replaced by rc2
UPDATE: the release has been delayed for two days
I've just released the release candidate for the final version of the Unix shell written in C language. Now with a very cleaner code and a lot of bugs fixed!
BD-shell 1.0.0 beta 1
Wednesday, July 30th, 2008I'm very proud to announce that the first beta version of the final release of BD-shell is ready and available for download.
As always you can find it on the project page.
Remember that this has to be considered as a bug hunting release, every requirements has been successfully covered but I cannot test it so often as I would like to..
Grab the code while it's hot!
A simple, tiny, Unix Shell written in C language, opensource
Friday, May 9th, 2008BD-shell is a project I started about a month ago, which aims to implement a tiny, simple, clean unix shell written in C language. It's an academic project. The Operating Systems Course at my University requires this project as part of the assesment.
I decided to publish the source code and to release it under the GPL, for two reasons:
- Free software is better! Others can learn something from what I learned
- Free software is better! I can learn something from what others learned
As always, I accept every kind of suggestions!
Learn more about the project and download the code at this page:
http://bd-things.net/projects/bd-shell/
Hash Maps with linear probing and separate chaining
Monday, April 28th, 2008Time for two new C programs! At the DSA course I learned something about Hash Tables and collision resolutions.
I just implemented insert/search/print operations.
The first source code is an implementation of a Hash Map with open addressing (linear probing) as collision resolution method.
The following are the interesting functions of the program. As always, take a look at the source code for comments:
// hashMapLinear[] is the hash map
void linearProbingInsert(int value){
int probe = hash(value);
while (hashMapLinear[probe]!=0){
probe = fmod((probe+1),SIZE_HASH_MAP);
}
hashMapLinear[probe] = value;
}
void linearProbingInsert(int value){
int probe = hash(value);
while (hashMapLinear[probe]!=0){
probe = fmod((probe+1),SIZE_HASH_MAP);
}
hashMapLinear[probe] = value;
}
int linearProbingSearch(int value){
int probe = hash(value);
int i;
for(i=0;i<size_hash_map ;i++){
if(hashMapLinear[probe]==value)
return TRUE;
probe = fmod((probe+1),SIZE_HASH_MAP);
}
return FALSE;
}
Download: hash-map-linear-probing.c
The second program is an implementation of a Hash Map with chaining as collision resolution method.
Interesting functions:
// t_hashTableNode is a struct that is created as single linked list
void chainedHashInsert(int value){
int probe = hash(value);
if(hashMapChained[probe] == NULL){
hashMapChained[probe] = malloc(sizeof(t_hashTableNode));
hashMapChained[probe]->value = value;
hashMapChained[probe]->next = NULL;
}else{
t_hashTableNode *hashTableNode = hashMapChained[probe];
while(hashTableNode->next!=NULL){
hashTableNode = hashTableNode->next;
}
hashTableNode->next = malloc(sizeof(t_hashTableNode));
hashTableNode->next->value = value;
hashTableNode->next->next = NULL;
}
}
void chainedHashInsert(int value){
int probe = hash(value);
if(hashMapChained[probe] == NULL){
hashMapChained[probe] = malloc(sizeof(t_hashTableNode));
hashMapChained[probe]->value = value;
hashMapChained[probe]->next = NULL;
}else{
t_hashTableNode *hashTableNode = hashMapChained[probe];
while(hashTableNode->next!=NULL){
hashTableNode = hashTableNode->next;
}
hashTableNode->next = malloc(sizeof(t_hashTableNode));
hashTableNode->next->value = value;
hashTableNode->next->next = NULL;
}
}
int chainedHashSearch(int value){
t_hashTableNode *hashTableNode = hashMapChained[hash(value)];
while(hashTableNode!=NULL){
if(hashTableNode->value==value){
return TRUE;
}
hashTableNode = hashTableNode->next;
}
return FALSE;
}
Download: hash-map-chaining.c