asm_minilibc

Mini glibc written in Assembly x86-64.

Compiled as shared library.

For more informations see man glibc.

Compile

compiling:

make

cleaning objects files:

make clean

cleaning binary files:

make fclean

cleaning all and compiling:

make re

How to use it

You just need to upload your minilibc library instead of the glibc library with this command

export LD_PRELOAD=./libasm.so

or execute your program with your minilibc library

LD_PRELOAD=./libasm.so ./a.out

Memory functions

Memcpy functions

The memcpy() function copies n bytes from memory area src to memory area dest. The memory areas must not overlap. Use memmove if the memory areas do overlap.

Memmove function

The memmove() function copies n bytes from memory area src to memory area dest. The memory areas may overlap: copying takes place as though the bytes in src are first copied into a temporary array that does not overlap src or dest, and the bytes are then copied from the temporary array to dest.

Memset function

The memset() function fills the first n bytes of the memory area pointed to by s with the constant byte c.

Comparaison functions

Strcmp function

The strcmp() function compares the two strings s1 and s2. It returns an integer less than, equal to, or greater than zero if s1 is found, respectively, to be less than, to match, or be greater than s2.

Strncmp function

The strncmp() function is similar to strcmp(), except it compares only the first (at most) n bytes of s1 and s2.

Strcasecmp function

The strcasecmp() function performs a byte-by-byte comparison of the strings s1 and s2, ignoring the case of the characters. It returns an integer less than, equal to, or greater than zero if s1 is found, respectively, to be less than, to match, or be greater than s2.

Strncasecmp function

The strncasecmp() function is similar to strcasecmp(), except that it compares no more than n bytes of s1 and s2.

Bytes occurence functions

Strchr function

The strchr() function returns a pointer to the first occurrence of the character c in the string s.

Strpbrk function

The strpbrk() function locates the first occurrence in the string s of any of the bytes in the string accept.

Strstr function

The strstr() function finds the first occurrence of the substring needle in the string haystack. The terminating null bytes ('\0') are not compared.

Rindex function

The rindex() function returns a pointer to the last occurrence of the character c in the string s.

Bytes lenght functions

Strcspn function

The strcspn() function calculates the length of the initial segment of s which consists entirely of bytes not in reject.

Strlen function

The strlen() function calculates the length of the string pointed to by s, excluding the terminating null byte ('\0').

File descriptor function

Read function

The read utility shall read a single line from standard input.

Write function

write() writes up to count bytes from the buffer pointed buf to the file referred to by the file descriptor fd.