1# Utils Development Guidelines<a name="EN-US_TOPIC_0000001059307279"></a> 2 3- [Available APIs](#section1633115419401) 4- [How to Develop](#section17450172710292) 5 - [Developing a Native Application for the KV Store That Uses the LiteOS Cortex-A Kernel \(Hi3516 or Hi3518\)](#section258354119295) 6 - [Dumping System Attributes on the Platform That Uses the LiteOS Cortex-M Kernel](#section9179161863014) 7 - [Dumping System Attributes on the Platform That Uses the LiteOS Cortex-A Kernel](#section3179121853017) 8 9 10## Available APIs<a name="section1633115419401"></a> 11 12**Table 1** APIs for file operations 13 14<a name="table1171894475019"></a> 15<table><thead align="left"><tr id="row1471814441508"><th class="cellrowborder" valign="top" width="45.540000000000006%" id="mcps1.2.3.1.1"><p id="p11718174425016"><a name="p11718174425016"></a><a name="p11718174425016"></a>Function</p> 16</th> 17<th class="cellrowborder" valign="top" width="54.459999999999994%" id="mcps1.2.3.1.2"><p id="p6718124475013"><a name="p6718124475013"></a><a name="p6718124475013"></a>Description</p> 18</th> 19</tr> 20</thead> 21<tbody><tr id="row671818445506"><td class="cellrowborder" valign="top" width="45.540000000000006%" headers="mcps1.2.3.1.1 "><p id="p871814441501"><a name="p871814441501"></a><a name="p871814441501"></a>int UtilsFileOpen(const char* path, int oflag, int mode)</p> 22</td> 23<td class="cellrowborder" valign="top" width="54.459999999999994%" headers="mcps1.2.3.1.2 "><p id="p127181444165016"><a name="p127181444165016"></a><a name="p127181444165016"></a>Opens or creates a file.</p> 24</td> 25</tr> 26<tr id="row1171874420507"><td class="cellrowborder" valign="top" width="45.540000000000006%" headers="mcps1.2.3.1.1 "><p id="p1671884419509"><a name="p1671884419509"></a><a name="p1671884419509"></a>int UtilsFileClose(int fd)</p> 27</td> 28<td class="cellrowborder" valign="top" width="54.459999999999994%" headers="mcps1.2.3.1.2 "><p id="p1071884416504"><a name="p1071884416504"></a><a name="p1071884416504"></a>Closes a file with a specified file descriptor.</p> 29</td> 30</tr> 31<tr id="row6718744105017"><td class="cellrowborder" valign="top" width="45.540000000000006%" headers="mcps1.2.3.1.1 "><p id="p137181644145015"><a name="p137181644145015"></a><a name="p137181644145015"></a>int UtilsFileRead(int fd, char *buf, unsigned int len)</p> 32</td> 33<td class="cellrowborder" valign="top" width="54.459999999999994%" headers="mcps1.2.3.1.2 "><p id="p1171854410509"><a name="p1171854410509"></a><a name="p1171854410509"></a>Reads a specified length of data from a file with the specified file descriptor and writes the data into the buffer.</p> 34</td> 35</tr> 36<tr id="row2071817440509"><td class="cellrowborder" valign="top" width="45.540000000000006%" headers="mcps1.2.3.1.1 "><p id="p17718144465012"><a name="p17718144465012"></a><a name="p17718144465012"></a>int UtilsFileWrite(int fd, const char *buf, unsigned int len)</p> 37</td> 38<td class="cellrowborder" valign="top" width="54.459999999999994%" headers="mcps1.2.3.1.2 "><p id="p67191444145012"><a name="p67191444145012"></a><a name="p67191444145012"></a>Writes a specified length of data into a file with the specified file descriptor.</p> 39</td> 40</tr> 41<tr id="row471974425019"><td class="cellrowborder" valign="top" width="45.540000000000006%" headers="mcps1.2.3.1.1 "><p id="p11719174475016"><a name="p11719174475016"></a><a name="p11719174475016"></a>int UtilsFileDelete(const char *path)</p> 42</td> 43<td class="cellrowborder" valign="top" width="54.459999999999994%" headers="mcps1.2.3.1.2 "><p id="p2071919446507"><a name="p2071919446507"></a><a name="p2071919446507"></a>Deletes a specified file.</p> 44</td> 45</tr> 46<tr id="row1071964425013"><td class="cellrowborder" valign="top" width="45.540000000000006%" headers="mcps1.2.3.1.1 "><p id="p20719114405010"><a name="p20719114405010"></a><a name="p20719114405010"></a>int UtilsFileStat(const char *path, unsigned int *fileSize)</p> 47</td> 48<td class="cellrowborder" valign="top" width="54.459999999999994%" headers="mcps1.2.3.1.2 "><p id="p8719144435015"><a name="p8719144435015"></a><a name="p8719144435015"></a>Obtains the file size.</p> 49</td> 50</tr> 51<tr id="row2071924417504"><td class="cellrowborder" valign="top" width="45.540000000000006%" headers="mcps1.2.3.1.1 "><p id="p57193447501"><a name="p57193447501"></a><a name="p57193447501"></a>int UtilsFileSeek(int fd, int offset, unsigned int whence)</p> 52</td> 53<td class="cellrowborder" valign="top" width="54.459999999999994%" headers="mcps1.2.3.1.2 "><p id="p1071934495014"><a name="p1071934495014"></a><a name="p1071934495014"></a>Adjusts the read and write position offset in a file.</p> 54</td> 55</tr> 56<tr id="row1135017417557"><td class="cellrowborder" valign="top" width="45.540000000000006%" headers="mcps1.2.3.1.1 "><p id="p2350184112554"><a name="p2350184112554"></a><a name="p2350184112554"></a>int UtilsFileCopy(const char* src, const char* dest)</p> 57</td> 58<td class="cellrowborder" valign="top" width="54.459999999999994%" headers="mcps1.2.3.1.2 "><p id="p113501041155511"><a name="p113501041155511"></a><a name="p113501041155511"></a>Copies the source file to a target file.</p> 59</td> 60</tr> 61<tr id="row11216645145517"><td class="cellrowborder" valign="top" width="45.540000000000006%" headers="mcps1.2.3.1.1 "><p id="p192171345105519"><a name="p192171345105519"></a><a name="p192171345105519"></a>int UtilsFileMove(const char* src, const char* dest)</p> 62</td> 63<td class="cellrowborder" valign="top" width="54.459999999999994%" headers="mcps1.2.3.1.2 "><p id="p921744595517"><a name="p921744595517"></a><a name="p921744595517"></a>Moves the source file into a target file.</p> 64</td> 65</tr> 66</tbody> 67</table> 68 69Sample code for file operations: 70 71``` 72// Open a file and write data. 73char fileName[] = "testfile"; 74static const char def[] = "utils_file_operation implement."; 75int fd = UtilsFileOpen(fileName, O_RDWR_FS | O_CREAT_FS | O_TRUNC_FS, 0); 76printf("file handle = %d\n", fd); 77int ret = UtilsFileWrite(fd, def, strlen(def)); 78printf("write ret = %d\n", ret); 79 80// Adjust the position offset in the file. 81ret = UtilsFileSeek(fd, 5, SEEK_SET_FS); 82printf("lseek ret = %d\n", ret); 83 84// Read data and close the file. 85char buf[64] = {0}; 86int readLen = UtilsFileRead(fd, buf, 64); 87ret = UtilsFileClose(fd); 88printf("read len = %d : buf = %s\n", readLen, buf); 89 90// Obtain the file size. 91int fileLen = 0; 92ret = UtilsFileStat(fileName, &fileLen); 93printf("file size = %d\n", fileLen); 94 95// Delete the file. 96ret = UtilsFileDelete(fileName); 97printf("delete ret = %d\n", ret); 98``` 99 100**Table 2** APIs for KV store operations 101 102<a name="table1731550155318"></a> 103<table><thead align="left"><tr id="row4419501537"><th class="cellrowborder" valign="top" width="57.38999999999999%" id="mcps1.2.3.1.1"><p id="p54150165315"><a name="p54150165315"></a><a name="p54150165315"></a>Function</p> 104</th> 105<th class="cellrowborder" valign="top" width="42.61%" id="mcps1.2.3.1.2"><p id="p941150145313"><a name="p941150145313"></a><a name="p941150145313"></a>Description</p> 106</th> 107</tr> 108</thead> 109<tbody><tr id="row34145016535"><td class="cellrowborder" valign="top" width="57.38999999999999%" headers="mcps1.2.3.1.1 "><p id="p980953910190"><a name="p980953910190"></a><a name="p980953910190"></a>int UtilsGetValue(const char* key, char* value, unsigned int len)</p> 110</td> 111<td class="cellrowborder" valign="top" width="42.61%" headers="mcps1.2.3.1.2 "><p id="p13562171015712"><a name="p13562171015712"></a><a name="p13562171015712"></a>Obtains the value matching a specified key from the file system or cache.</p> 112</td> 113</tr> 114<tr id="row1746172917474"><td class="cellrowborder" valign="top" width="57.38999999999999%" headers="mcps1.2.3.1.1 "><p id="p242913617818"><a name="p242913617818"></a><a name="p242913617818"></a>int UtilsSetValue(const char* key, const char* value)</p> 115</td> 116<td class="cellrowborder" valign="top" width="42.61%" headers="mcps1.2.3.1.2 "><p id="p2431455765"><a name="p2431455765"></a><a name="p2431455765"></a>Adds or updates the value matching a specified key in the file system or cache.</p> 117</td> 118</tr> 119<tr id="row10992232154714"><td class="cellrowborder" valign="top" width="57.38999999999999%" headers="mcps1.2.3.1.1 "><p id="p118151439111910"><a name="p118151439111910"></a><a name="p118151439111910"></a>int UtilsDeleteValue(const char* key)</p> 120</td> 121<td class="cellrowborder" valign="top" width="42.61%" headers="mcps1.2.3.1.2 "><p id="p126575774517"><a name="p126575774517"></a><a name="p126575774517"></a>Deletes the value matching a specified key from the file system or cache.</p> 122</td> 123</tr> 124</tbody> 125</table> 126 127Sample code for the KV store: 128 129``` 130// Set the value matching the specified key. 131char key[] = "rw.sys.version_100"; 132char value[] = "Hello kv operation implement!"; 133int ret = UtilsSetValue(key, value); 134printf("UtilsSetValue set ret = %d\n", ret); 135 136// Obtain the value matching the specified key. 137char temp[128] = {0}; 138ret = UtilsGetValue(key, temp, 128); 139printf("UtilsGetValue get ret = %d, temp = %s\n", ret, temp); 140 141// Delete the value matching the specified key. 142ret = UtilsDeleteValue(key); 143printf("UtilsDeleteValue delete ret = %d\n", ret); 144``` 145 146## How to Develop<a name="section17450172710292"></a> 147 148### Developing a Native Application for the KV Store That Uses the LiteOS Cortex-A Kernel \(Hi3516 or Hi3518\)<a name="section258354119295"></a> 149 1501. Develop the native application for the KV store using **AbilityKit** APIs. 151 - Write the user program by calling the APIs provided by the KV store and compile the **libLauncher.so** file. 152 153 ``` 154 // Set the value matching the specified key. 155 char key[] = "rw.sys.version_100"; 156 char value[] = "Hello kv operation implement!"; 157 int ret = UtilsSetValue(key, value); 158 printf("UtilsSetValue set ret = %d\n", ret); 159 160 // Obtain the value matching the specified key. 161 char temp[128] = {0}; 162 ret = UtilsGetValue(key, temp, 128); 163 printf("UtilsGetValue get ret = %d, temp = %s\n", ret, temp); 164 165 // Delete the value matching the specified key. 166 ret = UtilsDeleteValue(key); 167 printf("UtilsDeleteValue delete ret = %d\n", ret); 168 ``` 169 170 - Edit the **config.json** file as follows: 171 172 ``` 173 { 174 "app": { 175 "bundleName": "com.huawei.launcher", 176 "vendor": "huawei", 177 "version": { 178 "code": 1, 179 "name": "1.0" 180 } 181 }, 182 "deviceConfig": { 183 "default": { 184 "reqSdk": { 185 "compatible": "zsdk 1.0.0", 186 "target": "zsdk 1.0.1" 187 }, 188 "keepAlive": false 189 }, 190 "smartCamera": { 191 "reqSdk": { 192 "compatible": "zsdk 1.0.0", 193 "target": "zsdk 1.0.1" 194 }, 195 "keepAlive": false 196 } 197 }, 198 "module": { 199 "package": "com.huawei.launcher", 200 "name": ".MyHarmonyAbilityPackage", 201 "deviceType": [ 202 "phone", "tv","tablet", "pc","car","smartWatch","sportsWatch","smartCamera" 203 ], 204 "distro": { 205 "deliveryWithInstall": true, 206 "moduleName": "Launcher", 207 "moduleType": "entry" 208 }, 209 "abilities": [{ 210 "name": "MainAbility", 211 "icon": "res/drawable/phone.png", 212 "label": "test app 1", 213 "launchType": "standard", 214 "type": "page" 215 }, 216 { 217 "name": "SecondAbility", 218 "icon": "res/drawable/phone.png", 219 "label": "test app 2", 220 "launchType": "standard", 221 "type": "page" 222 }, 223 { 224 "name": "ServiceAbility", 225 "icon": "res/drawable/phone.png", 226 "label": "test app 2", 227 "launchType": "standard", 228 "type": "service" 229 } 230 ] 231 } 232 } 233 ``` 234 235 - Generate a HAP file. 236 237 - Add resource files in the **res/drawable** directory based on the following directory structure. 238 239  240 241 - Compress the **libLauncher.so**, **config.json**, and resource files into a ZIP package and change the file name extension to **.hap**, for example, **Launcher.hap**. 242 2432. Connect the development board and send the command for installing the native KV store application to the board through the serial port. 244 245 ``` 246 ./nfs/dev_tools/bin/bm install -p /nfs/Launcher.hap 247 ``` 248 2493. Send the command for running the native KV store application to the board through the serial port. 250 251 ``` 252 ./nfs/dev_tools/bin/aa start -p com.huawei.launcher -n ServiceAbility 253 ``` 254 255 256### Dumping System Attributes on the Platform That Uses the LiteOS Cortex-M Kernel<a name="section9179161863014"></a> 257 2581. Connect the development board and send the **AT+SYSPARA** command to the board through the serial port. 259 260 ``` 261 AT+SYSPARA 262 ``` 263 264 **Figure 1** Output of the system attribute dumping command for the LiteOS Cortex-M kernel<a name="fig15179161863016"></a> 265  266 267 268### Dumping System Attributes on the Platform That Uses the LiteOS Cortex-A Kernel<a name="section3179121853017"></a> 269 2701. Connect the development board and run the **os\_dump --help** command in the **bin** directory to view the **os\_dump** help information. 271 272 ``` 273 ./bin/os_dump --help 274 ``` 275 2762. Run the **os\_dump -l** command in the **bin** directory to view system modules that support attribute dumping. 277 278 ``` 279 ./bin/os_dump -l 280 ``` 281 2823. Run the **os\_dump syspara** command in the **bin** directory to dump the current system attributes. 283 284 ``` 285 ./bin/os_dump syspara 286 ``` 287 288 **Figure 2** Output of the system attribute dumping command for the LiteOS Cortex-A kernel<a name="fig2179718143018"></a> 289  290 291 292
