Reading a line of text from a stream

I would appreciate some comments on the code below for reading a line of 
text from a stream.


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

/**
 * Reads a line of text from a stream and returns the string on
 * success and NULL on failure. 
 * fstream - the stream to read from
 * maxRead - a variable that specifies the maximum number of
 * characters to read. If maxRead is NULL then SIZE_MAX-1 is
 * considered as the maximum value. If maxRead is different from NULL
 * then the function will set the value to the length of non-NULL
 * string returned by the function.
 * fullLine - a variable that specifies whether or not the end of line
 * has been reached (a complete line was read). It also returns true if 
EOF
 * has been reached. It can be set to NULL.
 */
char *readStringWithLimit(FILE *fstream, size_t *maxRead, 
        int *fullLine) {
    size_t capacityIncrement=256;
    size_t capacity=capacityIncrement;
    size_t readLimit;
    size_t stringLength=0;
    char *myStr, *tmpStr;
    int localFullLine;
    unsigned char c;
    int ic;

    if(maxRead==NULL) {
        readLimit=SIZE_MAX-1;
    } else {
        if((*maxRead)>SIZE_MAX-1) {
            readLimit=SIZE_MAX-1;
        } else {
            readLimit=*maxRead-1;
        }
    }

    myStr=malloc(capacity);
    if(!myStr) {
        return NULL;
    }
    while(1) {
        ic=fgetc(fstream);
        if(ic==EOF) {
            if(ferror(fstream)) {
                free(myStr);
                return NULL;
            } else {
                localFullLine=1;
                break;
            }
        } else {
            c=(unsigned char)ic;
            if(c=='\n') {
                localFullLine=1;
                break;
            } else {
                if(readLimit>=stringLength) {
                    if(stringLength==capacity) {
                        //calculate the necessary size
                        if(SIZE_MAX-capacityIncrement>capacity) {
                            capacity+=capacityIncrement;
                        } else {
                            capacity=SIZE_MAX;
                        }
                        tmpStr=realloc(myStr,capacity);
                        if(tmpStr) {
                            myStr=tmpStr;
                        } else {
                            free(myStr);
                            return NULL;
                        }
                    }
                    myStr[stringLength++]=c;
                } else {
                    ungetc(ic,fstream);
                    localFullLine=0;
                    break;
                }   
            }
        }
    }
    if(stringLength==capacity) {
        tmpStr=realloc(myStr,capacity+1);
        if(tmpStr) {
            myStr=tmpStr;
        } else {
            free(myStr);
            return NULL;
        }
    }
    myStr[stringLength]='\0';
    if(maxRead) {
        *maxRead=stringLength;
    }
    if(fullLine) {
        *fullLine=localFullLine;
    }
    return myStr;
}


Thank you.

-- 
Ioan - Ciprian Tandau
tandau _at_ freeshell _dot_ org (hope it's not too late)
(... and that it still works...)