程序代码：

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

char *getlines(gzFile file)
{
        size_t baselen = 10;
        char *line = (char *)malloc(baselen * sizeof(char));
        if(!line) exit(1);

        while(gzgets(file,line,baselen)!=NULL)
        {
                if(strstr(line,"\n"))   // 判断读入的内容时候含有换行符，此处有'\n'，表明完整的读完一行。
                {
                        line[strlen(line)-1]='\0';
                        return line;
                }
                else         // 没有读入换行符，只读入了一行的一部分； 此时重新分配内存，再次用gzgets读取， 直到读到换行符为止。                             
                {
                        do
                        {
                                baselen += 10;
                                line = (char *)realloc(line,baselen);
                                if(!line) exit(1);
                                gzgets(file,line,baselen);
                        }while(strstr(line,"\n")==NULL);

                        line[strlen(line)-1]='\0';
                        return line;
                }
        }
        line[strlen(line)-1]='\0';
        return line;
}

int main(int argc, char *argv[])
{
        gzFile fp=gzopen(argv[1],"r");
        if(!fp) exit(1);
        int cot =0;
        char *line;
        while((line=getlines(fp))!=NULL && !gzeof(fp)) 
        { 
                cot++; 
                printf("line %d\t%s\n",cot,line);
                free(line); 
        }
        gzclose(fp);
        exit(0);
}

程序代码：

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

typedef struct SHIT_FILE_ {
    FILE* file;
    char* line;
    int capacity;
} SHIT_FILE;

SHIT_FILE shit_open( const char* filename )
{
    return (SHIT_FILE){ fopen(filename,"rt"), NULL, 0 };
}

void shit_close( SHIT_FILE* pfile )
{
    if( pfile && pfile->file )
    {
        free( pfile->line );
        fclose( pfile->file );
        pfile->file = NULL;
        pfile->line = NULL;
        pfile->capacity = 0;
    }
}

char* shit_getline( SHIT_FILE* pfile )
{
    const int growth = 10;
    for( int offset=0; ; )
    {
        if( offset!=0 || pfile->capacity==0 )
        {
            char* tmp = realloc( pfile->line, pfile->capacity+growth );
            if( !tmp ) return NULL;
            pfile->line = tmp;
            pfile->capacity += growth;
        }

        if( fgets(pfile->line+offset,pfile->capacity-offset,pfile->file) )
        {
            size_t n = strlen( pfile->line+offset );
            if( pfile->line[offset+n-1] == '\n' )
            {
                pfile->line[offset+n-1] = '\0';
                return pfile->line;
            }
            offset += n;
        }
        else if( feof(pfile->file) )
            return offset!=0 ? pfile->line : NULL;
        else
            return NULL;
    }
    return NULL;
}

int main( int argc, char* argv[] )
{
    if( argc <= 1 )
        return 1;
    SHIT_FILE fp = shit_open( argv[1] );
    if( !fp.file ) return 1;

    size_t cot = 0;
    for( char* line; line=shit_getline(&fp), line; )
        printf( "line %zu: %s\n", ++cot, line );

    shit_close( &fp );
}