Parse /etc/mime.types in C, produce a linked-list of all mimetypes and filetype associations.

mimetypes.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#define MIMETYPE_MAX 32768*4
#define MIMETYPE_EXT_MAX_LENGTH 16
#define MIMETYPE_EXT_MAX_COUNT 16

// Linked list of our mimetypes:
struct s_mimetype {
	char	mimetype[64];
	int	 extensioncount;
	char	*extensions[MIMETYPE_EXT_MAX_COUNT];

	struct s_mimetype *next;
};

struct s_mimetype *mimes = NULL;

void read_mimetypes()
{
	FILE *fh = fopen("/etc/mime.types", "r");
	if( !fh )
	{
		fprintf(stderr, "Failed to read /etc/mime.types!\n");
		return;
	}

	// Slurp it into a big ol' buffer. If yours is larger than this, well, make this bigger.
	char *mimeraw = (char*)malloc( MIMETYPE_MAX+1 );
	size_t rin = fread( mimeraw, 1, MIMETYPE_MAX, fh );
	fclose( fh );
	mimeraw[ rin ] = '\0';

	bool onext = false;
	bool comment = false;
	struct s_mimetype *mime = (struct s_mimetype *)malloc(sizeof(struct s_mimetype));
	memset( mime, 0, sizeof(struct s_mimetype) );

	for( int x=0; mime && x < rin; x++ )
	{
		char ch = mimeraw[x];
		if( ch == '#' )
			comment = true;
		else if( ch == '\r' || ch == '\n' )
		{
			if( mime->mimetype[0] == '\0' )
			{
				// it's empty.
				onext = false;
				comment = false;
				continue;
			}

			// done this entry, move along now.
			mime->next = mimes;
			mimes = mime;
			mime = NULL;
			mime = (struct s_mimetype *)malloc(sizeof(struct s_mimetype));
			memset( mime, 0, sizeof(struct s_mimetype) );
			onext = false;
			comment = false;
			continue;
		}
		else if( comment )
			continue;
		else if( onext )
		{
			int extnum = mime->extensioncount - 1;
			int extlen = strlen( mime->extensions[extnum] );
			if( ch == ' ' || ch == '\t' )
			{
				// next one, or we're in padding still..
				if( extlen == 0 )
					continue;

				if( mime->extensioncount+1 >= MIMETYPE_EXT_MAX_COUNT )
				{
					// At our limit.
					comment = true;
					continue;
				}

				mime->extensioncount++;
				extnum++;
				mime->extensions[extnum] = (char *)malloc(MIMETYPE_EXT_MAX_LENGTH+1);
				mime->extensions[extnum][0] = '\0';
				continue;
			}
			else if( extlen < MIMETYPE_EXT_MAX_LENGTH )
			{
				mime->extensions[extnum][extlen] = ch;
				extlen++;
				mime->extensions[extnum][extlen] = '\0';
			}
		}
		else
		{
			int mlen = strlen( mime->mimetype );
			if( mlen >= sizeof(mime->mimetype) )
			{
				// At capacity!
				comment = true;
				continue;
			}
			else if( ch == ' ' || ch == '\t' )
			{
				onext = true;
				int extnum = mime->extensioncount;
				mime->extensions[extnum] = (char *)malloc(MIMETYPE_EXT_MAX_LENGTH+1);
				mime->extensions[extnum][0] = '\0';
				mime->extensioncount++;
				continue;
			}
			mime->mimetype[mlen] = ch;
			mlen++;
			mime->mimetype[mlen] = '\0';
		}
	}

	if( mime->mimetype[0] != '\0' )
	{
		mimes->next = mime;
		mimes = mime;
	}
	else
		free( mime );

	free( mimeraw );
}

void free_mimetypes()
{
	struct s_mimetype *mnext;
	for( struct s_mimetype *m=mimes; m; )
	{
		mnext = m->next;
		for( int x=0; x < m->extensioncount; x++ )
			free( m->extensions[x] );
		free( m );
		m = mnext;
	}
}

void spill_beans()
{
	for( struct s_mimetype *m=mimes; m; m=m->next )
	{
		printf("[%s] =>", m->mimetype);
		for( int x=0; x < m->extensioncount; x++ )
			printf(" (%s)", m->extensions[x]);

		printf("\n");
	}
}

int main(int argc, char **argv)
{
	read_mimetypes();

	spill_beans();

	free_mimetypes();

	return 0;
}