With this list, it should be clear why API hooking is useful. A small note to the reader, this post does not cover breakpoints, IAT Hooking, etc. The easiest way of hooking is by inserting a jump instruction. As you may or may not already know, the x86 instruction set has a variable length instruction size that is, an instruction can have a length between one byte and 16 bytes, at max.
Read in enough to fill your buffer, then dump your buffer to the screen, clear it out, and repeat until you get to the end of the file. Use fgets which takes a parameter to specify the buffer size, and which leaves any newline characters intact.
A simple loop over the file that prints the buffer content should naturally copy the file intact. Second, use fread or the common C idiom with fgetc.
These would process the file in fixed-size chunks or a single character at a time. If you must process the file over white-space delimited strings, then use either fgets or fread to read the file, and something like strtok to split the buffer at whitespace.
If there is an external requirement to use scanf to do the reading, then limit the length of the string it might read with a precision field in the format specifier. If single strings longer than your buffer are allowed, then you would have to process them in two pieces. If not, you have an opportunity to tell the user about an error politely without creating a buffer overflow security hole.
Regardless, always validate the return values and think about how to handle bad, malicious, or just malformed input.I have a text file named attheheels.com I want to write a C program that can read this file and print the content to the console (assume the file contains only ASCII text).
arch(1) - print machine hardware name (same as uname -m) b2sum(1) - compute and check BLAKE2 message digest base32(1) - base32 encode/decode data and print to standard output base64(1) - base64 encode/decode data and print to standard output basename(1) - strip directory and suffix from filenames cat(1) - concatenate files and print on the standard output chcon(1) - change file .
In C programming, file is a place on your physical disk where information is stored. Why files are needed? When a program is terminated, the entire data is lost.
arch(1) - print machine hardware name (same as uname -m) b2sum(1) - compute and check BLAKE2 message digest base32(1) - base32 encode/decode data and print to standard output base64(1) - base64 encode/decode data and print to standard output basename(1) - strip directory and suffix from filenames cat(1) - concatenate files and print on the standard output chcon(1) - change file security.
This function is identical to calling fopen(), fwrite() and fclose() successively to write data to a file.. If filename does not exist, the file is created. Otherwise, the existing file is overwritten, unless the FILE_APPEND flag is set.
In the last week's part 1 of my FAT and SD tutorial, we got as far as reading the file entries in root directory, and peeking into a file with hex editor. Now we'll cover the file allocation table itself to enable reading longer files, and adapt the code into a small footprint FAT16 library!
File allocation table in FAT16 In the previous part, we learned .