vsnprintf
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## Name

vsnprintf — Format a string and place it in a buffer

## Synopsis

`int vsnprintf (` | char * buf,
| size_t size,
| const char * fmt,
| va_list args`)`;

## Arguments

`buf`

  The buffer to place the result into

`size`

  The size of the buffer, including the trailing null space

`fmt`

  The format string to use

`args`

  Arguments for the format string

## Description

This function follows C99 vsnprintf, but has some extensions: `pS` output the name of a text symbol with offset `ps` output the name of a text symbol without offset `pF` output the name of a function pointer with its offset `pf` output the name of a function pointer without its offset `pB` output the name of a backtrace symbol with its offset `pR` output the address range in a struct resource with decoded flags `pr` output the address range in a struct resource with raw flags `pM` output a 6-byte MAC address with colons `pMR` output a 6-byte MAC address with colons in reversed order `pMF` output a 6-byte MAC address with dashes `pm` output a 6-byte MAC address without colons `pmR` output a 6-byte MAC address without colons in reversed order `pI4` print an IPv4 address without leading zeros `pi4` print an IPv4 address with leading zeros `pI6` print an IPv6 address with colons `pi6` print an IPv6 address without colons `pI6c` print an IPv6 address as specified by RFC 5952 `pIS` depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address `piS` depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address `pU`[bBlL] print a UUID/GUID in big or little endian using lower or upper case. %*ph[CDN] a variable-length hex string with a separator (supports up to 64 bytes of the input) `n` is ignored

** Please update Documentation/printk-formats.txt when making changes **

The return value is the number of characters which would be generated for the given input, excluding the trailing '\0', as per ISO C99. If you want to have the exact number of characters written into `buf` as return value (not including the trailing '\0'), use `vscnprintf`. If the return is greater than or equal to `size`, the resulting string is truncated.

If you're not already dealing with a va_list consider using `snprintf`.

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