System Calls mmapobj(2)
NAME
mmapobj - map a file object in the appropriate manner
SYNOPSIS
#include
int mmapobj(int fd, uint_t flags, mmapobj_result_t *storage,
uint_t *elements, void *arg);
PARAMETERS
fd The open file descriptor for the file to be mapped.flags Indicates that the default behavior of mmapobj()
should be modified accordingly. Available flags are:MMOBJ_INTERPRET
Interpret the contents of the file descrip-
tor instead of just mapping it as a single image. This flag can be used only with ELF and AOUT files.MMOBJ_PADDING
When mapping in the file descriptor, add an additional mapping before the lowest mapping and after the highest mapping. The size of this padding is at least as large as the amount pointed to by arg. These mappings will be private to the process, will notreserve any swap space and will have no pro-
tections. To use this address space, the protections for it will need to be changed. This padding request will be ignored for the AOUT format.storage A pointer to the mmapobj_result_t array where
the mapping data will be copied out after a suc-
cessful mapping of fd.elements A pointer to the number of mmapobj_result_t ele-
ments pointed to by storage. On return, ele-
ments contains the number of mappings required to fully map the requested object. If theSunOS 5.11 Last change: 1 Dec 2008 1
System Calls mmapobj(2)
original value of elements is too small, E2BIG is returned and elements is modified to contain the number of mappings necessary. arg A pointer to additional information that might be associated with the specific request. Onlythe MMOBJ_PADDING request uses this argument. If
MMOBJ_PADDING is not specified, arg must be
NULL.DESCRIPTION
The mmapobj() function establishes a set of mappings between
a process's address space and a file. By default, mmapobj()
maps the whole file as a single, private, read-only mapping.
The MMOBJ_INTERPRET flag instructs mmapobj() to attempt to
interpret the file and map the file according to the rules for that file format. The following ELF and AOUT formats are supported:ET_EXEC and AOUT executables
This format results in one or more mappings whose size, alignment and protections are as described by the file's program header information. The address of each mapping is explicitly defined by the file's program headers.ET_DYN and AOUT shared objects
This format results in one or more mappings whose size, alignment and protections are as described by the file'sprogram header information. The base address of the ini-
tial mapping is chosen by mmapobj(). The addresses of
adjacent mappings are based off of this base address as defined by the file's program headers.ET_REL and ET_CORE
This format results in a single, read-only mapping that
covers the whole file. The base address of this mappingis chosen by mmapobj().
The mmapobj() function will not map over any currently used
mappings within the process, except for the case of an ELFET_EXEC file for which a previous reservation has been made
via /dev/null. The most common way to make such a reserva-
tion would be with an mmap() of /dev/null.SunOS 5.11 Last change: 1 Dec 2008 2
System Calls mmapobj(2)
Mappings created with mmapobj() can be processed individu-
ally by other system calls such as munmap(2).The mmapobj_result structure contains the following members:
typedef struct mmapobj_result {
caddr_t mr_addr; /* mapping address */
size_t mr_msize; /* mapping size */
size_t mr_fsize; /* file size */
size_t mr_offset; /* offset into file */
uint_t mr_prot; /* the protections provided */
uint_t mr_flags; /* info on the mapping */
} mmapobj_result_t;
The macro MR_GET_TYPE(mr_flags) must be used when looking
for the above flags in the value of mr_flags.
Values for mr_flags include:
MR_PADDING 0x1 /* this mapping represents requested padding */
MR_HDR_ELF 0x2 /* the ELF header is mapped at mr_addr */
MR_HDR_AOU 0x3 /* the AOUT header is mapped at mr_addr */
When MR_PADDING is set, mr_fsize and mr_offset will both be
0.The mr_fsize member represents the amount of the file that
is mapped into memory with this mapping.The mr_offset member is the offset into the mapping where
valid data begins.The mr_msize member represents the size of the memory map-
ping starting at mr_addr. This size may include unused data
prior to mr_offset that exists to satisfy the alignment
requirements of this segment. This size may also include anynon-file data that are required to provide NOBITS data (typ-
ically .bss). The system reserves the right to map more thanmr_msize bytes of memory but only mr_msize bytes will be
available to the caller of mmapobj().
RETURN VALUES
SunOS 5.11 Last change: 1 Dec 2008 3
System Calls mmapobj(2)
Upon successful completion, 0 is returned and elements con-
tains the number of program headers that are mapped for fd. The data describing these elements are copied to storage such that the first elements members of the storage array contain valid mapping data.On failure, -1 is returned and errno is set to indicate the
error. No data is copied to storage.ERRORS
The mmapobj() function will fail if:
E2BIG The elements argument was not large enough to hold the number of loadable segments in fd.The elements argument will be modified to con-
tain the number of segments required. EACCES The file system containing the fd to be mapped does not allow execute access, or the file descriptor pointed to by fd is not open for reading. EADDRINUSE The mapping requirements overlap an object that is already used by the process. EAGAIN There is insufficient room to reserve swap space for the mapping. The file to be mapped is already locked using advisory or mandatory record locking. See fcntl(2). EBADF The fd argument is not a valid open file descriptor. EFAULT The storage, arg, or elements argument points to an invalid address. EINVAL The flags argument contains an invalid flag.MMOBJ_PADDING was not specified in flagsand
arg was non-null.
SunOS 5.11 Last change: 1 Dec 2008 4
System Calls mmapobj(2)
ENODEV The fd argument refers to an object for whichmmapobj() is meaningless, such as a terminal.
ENOMEM Insufficient memory is available to hold the program headers. Insufficient memory is available in the address space to create the mapping. ENOTSUP The current user data model does not match thefd to be interpreted; thus, a 32-bit process
that tried to use mmapobj() to interpret a
64-bit object would return ENOTSUP.
The fd argument is a file whose type can notbe interpreted and MMOBJ_INTERPRET was speci-
fied in flags. The ELF header contains an unalignede_phentsize value.
ENOSYS An unsupported filesystem operation was attempted while trying to map in the object.ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Private ||_____________________________|_____________________________|
| MT-Level | Async-Signal-Safe |
|_____________________________|_____________________________|
SEE ALSO
ld.so.1(1), fcntl(2), memcntl(2), mmap(2), mprotect(2), mun-
map(2), elf(3ELF), madvise(3C), mlockall(3C), msync(3C), a.out(4), attributes(5) Linker and Libraries GuideSunOS 5.11 Last change: 1 Dec 2008 5