hotspot/src/os/linux/vm/os_linux.cpp
// Loads .dll/.so and
// in case of error it checks if .dll/.so was built for the
// same architecture as Hotspot is running on
void * os::dll_load(const char *filename, char *ebuf, int ebuflen)
{
{- -------------------------------------------
(1) ::dlopen() が成功すればそれを返す.
---------------------------------------- -}
void * result= ::dlopen(filename, RTLD_LAZY);
if (result != NULL) {
// Successful loading
return result;
}
{- -------------------------------------------
(1) (以下は ::dlopen() が失敗した場合の処理.
失敗の原因を少し調べて分かりやすいエラーメッセージを返すようにしている.)
---------------------------------------- -}
Elf32_Ehdr elf_head;
// Read system error message into ebuf
// It may or may not be overwritten below
::strncpy(ebuf, ::dlerror(), ebuflen-1);
ebuf[ebuflen-1]='\0';
int diag_msg_max_length=ebuflen-strlen(ebuf);
char* diag_msg_buf=ebuf+strlen(ebuf);
if (diag_msg_max_length==0) {
// No more space in ebuf for additional diagnostics message
return NULL;
}
{- -------------------------------------------
(1.1) (ELF ファイルのヘッダ部分を取得する)
---------------------------------------- -}
int file_descriptor= ::open(filename, O_RDONLY | O_NONBLOCK);
if (file_descriptor < 0) {
// Can't open library, report dlerror() message
return NULL;
}
bool failed_to_read_elf_head=
(sizeof(elf_head)!=
(::read(file_descriptor, &elf_head,sizeof(elf_head)))) ;
::close(file_descriptor);
if (failed_to_read_elf_head) {
// file i/o error - report dlerror() msg
return NULL;
}
{- -------------------------------------------
(1.1) (以下は調査用の型/定数の宣言)
---------------------------------------- -}
typedef struct {
Elf32_Half code; // Actual value as defined in elf.h
Elf32_Half compat_class; // Compatibility of archs at VM's sense
char elf_class; // 32 or 64 bit
char endianess; // MSB or LSB
char* name; // String representation
} arch_t;
#ifndef EM_486
#define EM_486 6 /* Intel 80486 */
#endif
static const arch_t arch_array[]={
{EM_386, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
{EM_486, EM_386, ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
{EM_IA_64, EM_IA_64, ELFCLASS64, ELFDATA2LSB, (char*)"IA 64"},
{EM_X86_64, EM_X86_64, ELFCLASS64, ELFDATA2LSB, (char*)"AMD 64"},
{EM_SPARC, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
{EM_SPARC32PLUS, EM_SPARC, ELFCLASS32, ELFDATA2MSB, (char*)"Sparc 32"},
{EM_SPARCV9, EM_SPARCV9, ELFCLASS64, ELFDATA2MSB, (char*)"Sparc v9 64"},
{EM_PPC, EM_PPC, ELFCLASS32, ELFDATA2MSB, (char*)"Power PC 32"},
{EM_PPC64, EM_PPC64, ELFCLASS64, ELFDATA2MSB, (char*)"Power PC 64"},
{EM_ARM, EM_ARM, ELFCLASS32, ELFDATA2LSB, (char*)"ARM"},
{EM_S390, EM_S390, ELFCLASSNONE, ELFDATA2MSB, (char*)"IBM System/390"},
{EM_ALPHA, EM_ALPHA, ELFCLASS64, ELFDATA2LSB, (char*)"Alpha"},
{EM_MIPS_RS3_LE, EM_MIPS_RS3_LE, ELFCLASS32, ELFDATA2LSB, (char*)"MIPSel"},
{EM_MIPS, EM_MIPS, ELFCLASS32, ELFDATA2MSB, (char*)"MIPS"},
{EM_PARISC, EM_PARISC, ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
{EM_68K, EM_68K, ELFCLASS32, ELFDATA2MSB, (char*)"M68k"}
};
#if (defined IA32)
static Elf32_Half running_arch_code=EM_386;
#elif (defined AMD64)
static Elf32_Half running_arch_code=EM_X86_64;
#elif (defined IA64)
static Elf32_Half running_arch_code=EM_IA_64;
#elif (defined __sparc) && (defined _LP64)
static Elf32_Half running_arch_code=EM_SPARCV9;
#elif (defined __sparc) && (!defined _LP64)
static Elf32_Half running_arch_code=EM_SPARC;
#elif (defined __powerpc64__)
static Elf32_Half running_arch_code=EM_PPC64;
#elif (defined __powerpc__)
static Elf32_Half running_arch_code=EM_PPC;
#elif (defined ARM)
static Elf32_Half running_arch_code=EM_ARM;
#elif (defined S390)
static Elf32_Half running_arch_code=EM_S390;
#elif (defined ALPHA)
static Elf32_Half running_arch_code=EM_ALPHA;
#elif (defined MIPSEL)
static Elf32_Half running_arch_code=EM_MIPS_RS3_LE;
#elif (defined PARISC)
static Elf32_Half running_arch_code=EM_PARISC;
#elif (defined MIPS)
static Elf32_Half running_arch_code=EM_MIPS;
#elif (defined M68K)
static Elf32_Half running_arch_code=EM_68K;
#else
#error Method os::dll_load requires that one of following is defined:\
IA32, AMD64, IA64, __sparc, __powerpc__, ARM, S390, ALPHA, MIPS, MIPSEL, PARISC, M68K
#endif
{- -------------------------------------------
(1.1) (ELF ファイルのヘッダ部を調査する)
---------------------------------------- -}
// Identify compatability class for VM's architecture and library's architecture
// Obtain string descriptions for architectures
arch_t lib_arch={elf_head.e_machine,0,elf_head.e_ident[EI_CLASS], elf_head.e_ident[EI_DATA], NULL};
int running_arch_index=-1;
for (unsigned int i=0 ; i < ARRAY_SIZE(arch_array) ; i++ ) {
if (running_arch_code == arch_array[i].code) {
running_arch_index = i;
}
if (lib_arch.code == arch_array[i].code) {
lib_arch.compat_class = arch_array[i].compat_class;
lib_arch.name = arch_array[i].name;
}
}
assert(running_arch_index != -1,
"Didn't find running architecture code (running_arch_code) in arch_array");
{- -------------------------------------------
(1.1) (分からなかった場合は dlerror() が返すエラーメッセージをそのまま使う)
---------------------------------------- -}
if (running_arch_index == -1) {
// Even though running architecture detection failed
// we may still continue with reporting dlerror() message
return NULL;
}
{- -------------------------------------------
(1.1) (endiann が異なる場合)
---------------------------------------- -}
if (lib_arch.endianess != arch_array[running_arch_index].endianess) {
::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: endianness mismatch)");
return NULL;
}
{- -------------------------------------------
(1)
---------------------------------------- -}
#ifndef S390
if (lib_arch.elf_class != arch_array[running_arch_index].elf_class) {
::snprintf(diag_msg_buf, diag_msg_max_length-1," (Possible cause: architecture word width mismatch)");
return NULL;
}
#endif // !S390
{- -------------------------------------------
(1)
---------------------------------------- -}
if (lib_arch.compat_class != arch_array[running_arch_index].compat_class) {
if ( lib_arch.name!=NULL ) {
::snprintf(diag_msg_buf, diag_msg_max_length-1,
" (Possible cause: can't load %s-bit .so on a %s-bit platform)",
lib_arch.name, arch_array[running_arch_index].name);
} else {
::snprintf(diag_msg_buf, diag_msg_max_length-1,
" (Possible cause: can't load this .so (machine code=0x%x) on a %s-bit platform)",
lib_arch.code,
arch_array[running_arch_index].name);
}
}
return NULL;
}
This document is available under the GNU GENERAL PUBLIC LICENSE Version 2.