bt_sprnf_addrs()

Format the addresses from a backtrace

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The backtrace library is an unsupported feature, due to its fragility. For more information, see Backtraces in the QNX Neutrino technotes.

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Synopsis:

#include <backtrace.h>

int bt_sprnf_addrs( bt_memmap_t *memmap,
                    bt_addr_t *addrs,
                    int addrslen,
                    char *fmt,
                    char *out,
                    size_t outlen,
                    char *separator );

Arguments:

memmap

NULL, or a pointer to memory-map information for the process you've collected backtracing for. Use bt_load_memmap() to initialize this variable.

addrs

An array of addresses that you want to format.

addrslen

The number of entries in the addrs array.

fmt

The format to use for each entry; see below.

out

A pointer to a buffer where the function can store the formatted output.

outlen

The length of the out, in bytes.

separator

NULL, or a pointer to a separator to write between the formatted addresses.

Library:

libbacktrace

Use the -l backtrace option to qcc to link against this library.

Description:

The bt_sprnf_addrs() function formats the addresses in the addrs using fmt as the format for each entry, and storing the formatted addresses in the out buffer. If separator isn't NULL, the function writes it in out between each formatted address.

The memmap is optional, but if specified, it allows access to more formatting styles. The format for each entry (fmt), is analogous to printf() formats:

• %% — a literal %.
• %a — an address in memory.
• %l — an address relative to the start of the file it belongs to (i.e. this corresponds to the address in the object file).
• %o — an address offset from the beginning of the object files. (i.e. %a == %l + %o).
• %f — an object file that the address belongs to (e.g. /some/dir/libc.so).
• %I — a numerical index that corresponds to the numerical index in the memory map printouts (i.e. if the memory map is printed, then using %I instead of %f in the backtrace minimizes the size of the backtrace).

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For the %l, %o, %f, and %I formats, memmap must not be NULL.

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Returns:

The number of addresses from addr that could be completely formatted and written in out.

Classification:

QNX Neutrino

See also:

bt_get_backtrace(), bt_init_accessor(), bt_load_memmap(), bt_release_accessor(), bt_set_flags(), bt_sprn_memmap(), bt_translate_addrs(), bt_unload_memmap()

Backtraces in the QNX Neutrino technotes

pidin backtrace in the Utilities Reference