1 /* 2 * Hosted file support for semihosting syscalls. 3 * 4 * Copyright (c) 2005, 2007 CodeSourcery. 5 * Copyright (c) 2019 Linaro 6 * Copyright © 2020 by Keith Packard <keithp@keithp.com> 7 * 8 * SPDX-License-Identifier: GPL-2.0-or-later 9 */ 10 11 #include "qemu/osdep.h" 12 #include "gdbstub/syscalls.h" 13 #include "semihosting/semihost.h" 14 #include "semihosting/guestfd.h" 15 #ifndef CONFIG_USER_ONLY 16 #include CONFIG_DEVICES 17 #endif 18 19 static GArray *guestfd_array; 20 21 #ifdef CONFIG_ARM_COMPATIBLE_SEMIHOSTING 22 GuestFD console_in_gf; 23 GuestFD console_out_gf; 24 #endif 25 26 void qemu_semihosting_guestfd_init(void) 27 { 28 /* New entries zero-initialized, i.e. type GuestFDUnused */ 29 guestfd_array = g_array_new(FALSE, TRUE, sizeof(GuestFD)); 30 31 #ifdef CONFIG_ARM_COMPATIBLE_SEMIHOSTING 32 /* For ARM-compat, the console is in a separate namespace. */ 33 if (use_gdb_syscalls()) { 34 console_in_gf.type = GuestFDGDB; 35 console_in_gf.hostfd = 0; 36 console_out_gf.type = GuestFDGDB; 37 console_out_gf.hostfd = 2; 38 } else { 39 console_in_gf.type = GuestFDConsole; 40 console_out_gf.type = GuestFDConsole; 41 } 42 #else 43 /* Otherwise, the stdio file descriptors apply. */ 44 guestfd_array = g_array_set_size(guestfd_array, 3); 45 #ifndef CONFIG_USER_ONLY 46 if (!use_gdb_syscalls()) { 47 GuestFD *gf = &g_array_index(guestfd_array, GuestFD, 0); 48 gf[0].type = GuestFDConsole; 49 gf[1].type = GuestFDConsole; 50 gf[2].type = GuestFDConsole; 51 return; 52 } 53 #endif 54 associate_guestfd(0, 0); 55 associate_guestfd(1, 1); 56 associate_guestfd(2, 2); 57 #endif 58 } 59 60 /* 61 * Allocate a new guest file descriptor and return it; if we 62 * couldn't allocate a new fd then return -1. 63 * This is a fairly simplistic implementation because we don't 64 * expect that most semihosting guest programs will make very 65 * heavy use of opening and closing fds. 66 */ 67 int alloc_guestfd(void) 68 { 69 guint i; 70 71 /* SYS_OPEN should return nonzero handle on success. Start guestfd from 1 */ 72 for (i = 1; i < guestfd_array->len; i++) { 73 GuestFD *gf = &g_array_index(guestfd_array, GuestFD, i); 74 75 if (gf->type == GuestFDUnused) { 76 return i; 77 } 78 } 79 80 /* All elements already in use: expand the array */ 81 g_array_set_size(guestfd_array, i + 1); 82 return i; 83 } 84 85 static void do_dealloc_guestfd(GuestFD *gf) 86 { 87 gf->type = GuestFDUnused; 88 } 89 90 /* 91 * Look up the guestfd in the data structure; return NULL 92 * for out of bounds, but don't check whether the slot is unused. 93 * This is used internally by the other guestfd functions. 94 */ 95 static GuestFD *do_get_guestfd(int guestfd) 96 { 97 if (guestfd < 0 || guestfd >= guestfd_array->len) { 98 return NULL; 99 } 100 101 return &g_array_index(guestfd_array, GuestFD, guestfd); 102 } 103 104 /* 105 * Given a guest file descriptor, get the associated struct. 106 * If the fd is not valid, return NULL. This is the function 107 * used by the various semihosting calls to validate a handle 108 * from the guest. 109 * Note: calling alloc_guestfd() or dealloc_guestfd() will 110 * invalidate any GuestFD* obtained by calling this function. 111 */ 112 GuestFD *get_guestfd(int guestfd) 113 { 114 GuestFD *gf = do_get_guestfd(guestfd); 115 116 if (!gf || gf->type == GuestFDUnused) { 117 return NULL; 118 } 119 return gf; 120 } 121 122 /* 123 * Associate the specified guest fd (which must have been 124 * allocated via alloc_fd() and not previously used) with 125 * the specified host/gdb fd. 126 */ 127 void associate_guestfd(int guestfd, int hostfd) 128 { 129 GuestFD *gf = do_get_guestfd(guestfd); 130 131 assert(gf); 132 gf->type = use_gdb_syscalls() ? GuestFDGDB : GuestFDHost; 133 gf->hostfd = hostfd; 134 } 135 136 void staticfile_guestfd(int guestfd, const uint8_t *data, size_t len) 137 { 138 GuestFD *gf = do_get_guestfd(guestfd); 139 140 assert(gf); 141 gf->type = GuestFDStatic; 142 gf->staticfile.data = data; 143 gf->staticfile.len = len; 144 gf->staticfile.off = 0; 145 } 146 147 /* 148 * Deallocate the specified guest file descriptor. This doesn't 149 * close the host fd, it merely undoes the work of alloc_fd(). 150 */ 151 void dealloc_guestfd(int guestfd) 152 { 153 GuestFD *gf = do_get_guestfd(guestfd); 154 155 assert(gf); 156 do_dealloc_guestfd(gf); 157 } 158